Polyethylene compositions, method of producing the same, articles made therefrom, and method of making the same

ABSTRACT

The instant invention is a polyethylene composition, method of producing the same, articles made therefrom, and method of making the same. The polyethylene composition according to the instant invention comprises (1) less than or equal to 100 percent by weight of the units derived from ethylene; and (2) less than 15 percent by weight of units derived from one or more α-olefin comonomers. The polyethylene composition according the instant invention has a density in the range of 0.907 to 0.975 g/cm 3 , a molecular weight distribution (M w /M n ) in the range of 1.70 to 3.62, a melt index (I 2 ) in the range of 2 to 1000 g/10 minutes, a molecular weight distribution (M z /M w ) in the range of less than 2.5, and a vinyl unsaturation of less than 0.06 vinyls per one thousand carbon atoms present in the backbone of the composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This present application is a continuation application of U.S.application Ser. No. 12/663,871, filed on Jan. 23, 2009, which claimspriority from U.S. Application No. 61/024,237, filed Jan. 29, 2008; eachapplication is incorporated herein, in its entirety, by reference.

FIELD OF INVENTION

The instant invention relates to polyethylene compositions, method ofproducing the same, articles made therefrom, and method of making thesame.

BACKGROUND OF THE INVENTION

The use of polyethylene compositions, such as linear low densitypolyethylenes and/or high density polyethylenes, in fabrication ofinjection molded articles is generally known. Any conventional method,such as gas phase process, slurry process, solution process or highpressure process, may be employed to produce such polyethylenecompositions.

In general, in the injection molding process, a polyethylene compositionis fed into an extruder via a hopper. The extruder conveys, heats,melts, and pressurizes the polyethylene composition to a form a moltenstream. The molten stream is forced out of the extruder under pressurethrough a nozzle into a relatively cool mold held closed thereby fillingthe mold under pressure. The melt cools and hardens until fully set-up.The mold then is opened and the molded article, e.g. tote, dish pan,waist container, bottle cap, is removed.

Various polymerization techniques using different catalyst systems havebeen employed to produce such polyethylene compositions suitable forinjection molding applications. However, the currently availablepolyethylene compositions fail to provide a stiffness/toughness balancethat is required for injection moldings applications, e.g. thin wallarticles with improved cold temperature performance.

Despite the research efforts in developing polyethylene compositionssuitable for injection molding, there is still a need for a polyethylenecomposition having a narrow molecular weight distribution, narrowcomposition distribution, and improved low and room temperature impactresistance while maintaining stiffness and processability properties.Additionally, there is a need for a method of producing suchpolyethylene compositions having a narrow molecular weight distribution,narrow composition distribution, and improved low temperature impactresistance while maintaining stiffness and processability properties.

SUMMARY OF THE INVENTION

The instant invention is a polyethylene composition, method of producingthe same, articles made therefrom, and method of making the same. Thepolyethylene composition according to the instant invention comprises(1) less than or equal to 100 percent by weight of the units derivedfrom ethylene; and (2) less than 15 percent by weight of units derivedfrom one or more α-olefin comonomers. The polyethylene compositionaccording the instant invention has a density in the range of 0.907 to0.975 g/cm³, a molecular weight distribution (M_(w)/M_(n)) in the rangeof 1.70 to 3.62, a melt index (I₂) in the range of 2 to 1000 g/10minutes, a molecular weight distribution (M_(z)/M_(w)) in the range ofless than 2.5, and a vinyl unsaturation of less than 0.06 vinyls per onethousand carbon atoms present in the backbone of the composition. Theprocess for producing a polyethylene composition according to theinstant invention comprises the steps of: (1) (co)polymerizing ethyleneand optionally one or more α-olefin comonomers in the presence of ahafnium based metallocene catalyst via a gas phase (co)polymerizationprocess in a single stage reactor; and (2) thereby producing theinventive polyethylene composition, wherein the polyethylene compositionhas a density in the range of 0.907 to 0.975 g/cm³, a molecular weightdistribution (M_(w)/M_(n)) in the range of 1.70 to 3.62, a melt index(I₂) in the range of 2 to 1000 g/10 minutes, a molecular weightdistribution (M_(z)/M_(w)) in the range of less than 2.5, and a vinylunsaturation of less than 0.06 vinyls per one thousand carbon atomspresent in the backbone of said composition. The injection moldedarticles according to the instant invention comprise a polyethylenecomposition comprising (1) less than or equal to 100 percent by weightof the units derived from ethylene; and (2) less than 15 percent byweight of units derived from one or more α-olefin comonomers; whereinthe polyethylene composition has a density in the range of 0.907 to0.975 g/cm³, a molecular weight distribution (M_(w)/M_(n)) in the rangeof 1.70 to 3.62, a melt index (I₂) in the range of 2 to 1000 g/10minutes, a molecular weight distribution (M_(z)/M_(w)) in the range ofless than 2.5, vinyl unsaturation of less than 0.06 vinyls per onethousand carbon atoms present in the backbone of said composition. Theprocess for making an injection molded article according to the instantinvention comprises the steps of: (a) selecting a polyethylenecomposition comprising (1) less than or equal to 100 percent by weightof the units derived from ethylene; and (2) less than 15 percent byweight of units derived from one or more α-olefin comonomers; whereinthe polyethylene composition has a density in the range of 0.907 to0.975 g/cm³, a molecular weight distribution (M_(w)/M_(n)) in the rangeof 1.70 to 3.62, a melt index (I₂) in the range of 2 to 1000 g/10minutes, a molecular weight distribution (M_(z)/M_(w)) in the range ofless than 2.5, vinyl unsaturation of less than 0.06 vinyls per onethousand carbon atoms present in the backbone of said composition; (b)injection molding said polyethylene composition; and (c) thereby formingthe injection molded article.

In one embodiment, the instant invention provides a polyethylenecomposition comprising (1) less than or equal to 100 percent by weightof the units derived from ethylene; and (2) less than 15 percent byweight of units derived from one or more α-olefin comonomers, whereinthe polyethylene composition has a density in the range of 0.907 to0.975 g/cm³, a molecular weight distribution (M_(w)/M_(n)) in the rangeof 1.70 to 3.62, a melt index (I₂) in the range of 2 to 1000 g/10minutes, a molecular weight distribution (M_(z)/M_(w)) in the range ofless than 2.5, and a vinyl unsaturation of less than 0.06 vinyls per onethousand carbon atoms present in the backbone of the composition.

In an alternative embodiment, the instant invention further provides apolyethylene composition comprising the (co)polymerization reactionproduct of ethylene and optionally one or more α-olefin comonomers inthe presence of a hafnium based metallocene catalyst via a gas phase(co)polymerization process in a single stage reactor; wherein thepolyethylene composition has a density in the range of 0.907 to 0.975g/cm³, a molecular weight distribution (M_(w)/M_(n)) in the range of1.70 to 3.62, a melt index (I₂) in the range of 2 to 1000 g/10 minutes,a molecular weight distribution (M_(z)/M_(w)) in the range of less than2.5, and a vinyl unsaturation of less than 0.06 vinyls per one thousandcarbon atoms present in the backbone of the composition.

In another alternative embodiment, the instant invention furtherprovides a process for producing a polyethylene composition comprisingthe steps of: (1) (co)polymerizing ethylene and optionally one or moreα-olefin comonomers in the presence of a hafnium based metallocenecatalyst via a gas phase (co)polymerization process in a single stagereactor; and (2) thereby producing the inventive polyethylenecomposition, wherein polyethylene composition according the instantinvention has a density in the range of 0.907 to 0.975 g/cm³, amolecular weight distribution (M_(w)/M_(n)) in the range of 1.70 to3.62, a melt index (I₂) in the range of 2 to 1000 g/10 minutes, amolecular weight distribution (M_(z)/M_(w)) in the range of less than2.5, and a vinyl unsaturation of less than 0.06 vinyls per one thousandcarbon atoms present in the backbone of said composition.

In another alternative embodiment, the instant invention furtherprovides an injection molded article comprising a polyethylenecomposition comprising (1) less than or equal to 100 percent by weightof the units derived from ethylene; and (2) less than 15 percent byweight of units derived from one or more α-olefin comonomers; whereinsaid polyethylene composition has a density in the range of 0.907 to0.975 g/cm³, a molecular weight distribution (M_(w)/M_(n)) in the rangeof 1.70 to 3.62, a melt index (I₂) in the range of 2 to 1000 g/10minutes, a molecular weight distribution (M_(z)/M_(w)) in the range ofless than 2.5, vinyl unsaturation of less than 0.06 vinyls per onethousand carbon atoms present in the backbone of said composition.

In another alternative embodiment, the instant invention furtherprovides a process for making an article comprising the steps of: (a)selecting a polyethylene composition comprising (1) less than or equalto 100 percent by weight of the units derived from ethylene; and (2)less than 15 percent by weight of units derived from one or moreα-olefin comonomers; wherein said polyethylene composition has a densityin the range of 0.907 to 0.975 g/cm³, a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 3.62, a melt index (I₂) in therange of 2 to 1000 g/10 minutes, a molecular weight distribution(M_(z)/M_(w)) in the range of less than 2.5, vinyl unsaturation of lessthan 0.06 vinyls per one thousand carbon atoms present in the backboneof said composition; (b) injection molding said polyethylenecomposition; and (c) thereby forming said injection molded article.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa density in the range of 0.911 to 0.972 g/cm³.

In another alternative embodiment, the instant invention provides acomposition, method of producing the same, articles made therefrom, andmethod of making such articles, in accordance with any of the precedingembodiments, except that the polyethylene composition has a vinylunsaturation of less than 0.05 vinyls per one thousand carbon atomspresent in the backbone of the composition.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa molecular weight distribution (M_(w)/M_(n)) of less than[(−16.18))(D)]+18.83, wherein D is the density of the polyethylenecomposition in the range of greater than 0.940 g/cm³ to less than orequal to 0.975 g/cm³.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa density in the range of 0.924 to 0.930 g/cm³, and a melt index (I₂) inthe range of 40 to 80 g/10 minutes.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa density in the range of 0.926 to 0.936 g/cm³, and a melt index (I₂) inthe range of 80 to 250 g/10 minutes.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa density in the range of 0.940 to 0.946 g/cm³, and a melt index (I₂) inthe range of 100 to 300 g/10 minutes.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa density in the range of 0.946 to 0.953 g/cm³, and a melt index (I₂) inthe range of 60 to 110 g/10 minutes.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa density in the range of 0.948 to 0.956 g/cm³, and a melt index (I₂) inthe range of 30 to 90 g/10 minutes.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa density in the range of 0.946 to 0.956 g/cm³, and a melt index (I₂) inthe range of 3 to 30 g/10 minutes.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa density of approximately equal to D, wherein D=[(0.0034 (Ln(I₂))+0.9553], wherein I₂ is melt index expressed in g/10 min.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa short chain branching distribution breadth (SCBDB) expressed in ° C.of less than or equal to [0.025 (I₂)+4.08], wherein I₂ is melt indexexpressed in g/10 min, and wherein the composition has a density in therange of equal or greater than 0.930 g/cm³ to less than 0.940 g/cm³.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa short chain branching distribution breadth (SCBDB) expressed in ° C.of less than or equal to [0.0312 (I₂)+2.87], wherein I₂ is melt indexexpressed in g/10 min, and wherein the polyethylene composition has adensity in the range of equal or greater than 0.940 g/cm³.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa tensile impact expressed in ft-lb/in² of equal or greater than[(−6.53*10⁻⁵)(x⁴)]+[(1.3*10⁻²)(x³)]−[(9.68*10⁻¹)(x²)]+[(3.22*10)(x)]−[(3.69*10²)],wherein x is the shear viscosity of the composition expressed inPascal-s at 3000 s⁻¹ shear rate measured at 190° C., wherein the shearviscosity is in the range of 25 to 55 Pascal-s at 3000 s⁻¹ shear ratemeasured at 190° C., and wherein the modulus of the composition is inthe range of 75,000 to 115,000 psi.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasless than 2 peaks on an elution temperature-eluted amount curvedetermined by continuous temperature rising elution fraction method atequal or above 30° C., wherein the purge peak which is below 30° C. isexcluded.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasonly 1 peak on an elution temperature-eluted amount curve determined bycontinuous temperature rising elution fraction method at equal or above30° C., wherein the purge peak which is below 30° C. is excluded.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa molecular weight distribution (Mz/Mw) in the range of less than 2.3.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene compositioncomprises less than 11 percent by weight of the units derived from oneor more α-olefin comonomers.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene compositioncomprises less than 9 percent by weight of the units derived from one ormore α-olefin comonomers.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene compositioncomprises less than 7 percent by weight of the units derived from one ormore α-olefin comonomers.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene compositioncomprises less than 5 percent by weight of the units derived from one ormore α-olefin comonomers.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene compositioncomprises less than 3 percent by weight of the units derived from one ormore α-olefin comonomers.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition issubstantially free of any long chain branching.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition isfree of any long chain branching.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene compositionfurther comprises less than 100 parts by weight of hafnium residuesremaining from the hafnium based metallocene catalyst per one millionparts of polyethylene composition.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa melt flow ratio (I₂₁/I₂) in the range of 17 to 24.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa melt flow ratio (I₂₁/I₂) in the range of 17 to 23.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa melt flow ratio (I₂₁/I₂) in the range of 21 to 24.

In another alternative embodiment, the instant invention provides apolyethylene composition, method of producing the same, articles madetherefrom, and method of making such articles, in accordance with any ofthe preceding embodiments, except that the polyethylene composition hasa melt index I₂₁ in the range of 34 to 24000 g/10 minutes.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in thedrawings a form that is exemplary; it being understood, however, thatthis invention is not limited to the precise arrangements andinstrumentalities shown.

FIG. 1 illustrates the relationship between the short chain branchingdistribution breadth expressed in ° C. and melt index (I₂) expressed ing/10 minutes of the inventive samples versus the comparative samples,wherein the inventive samples have a density in the range of equal orgreater than 0.940 g/cm³;

FIG. 2 illustrates the relationship between the short chain branchingdistribution breadth expressed in ° C. and melt index (I₂) expressed ing/10 minutes of the inventive samples versus the comparative samples,wherein the inventive samples have a density in the range of 0.930 toless than 0.940 g/cm³;

FIG. 3 illustrates the relationship between the molecular weightdistribution (M_(w)/M_(n)) and density expressed in g/cm³ of theinventive samples versus the comparative samples;

FIG. 4 illustrates the relationship between the tensile impact expressedin ft-lbs/in² and shear viscosity at 3000 s⁻¹ at 190° C. expressed inPa-s of the inventive samples versus the comparative samples;

FIG. 5 illustrates the relationship between the vinyl unsaturations per1000 carbons and density expressed in g/cm³ of the inventive samplesversus the comparative samples;

FIG. 6 is the elution temperature-eluted amount curve of a firstinventive polyethylene composition having a melt index (I₂) ofapproximately 40 g/10 minutes determined by a continuous temperaturerising elution fraction method at equal or above 30° C., wherein thepurge peak which is below 30° C. is excluded;

FIG. 7 is the elution temperature-eluted amount curve of a secondinventive polyethylene composition having a melt index (I₂) ofapproximately 80 g/10 minutes determined by a continuous temperaturerising elution fraction method at equal or above 30° C., wherein thepurge peak which is below 30° C. is excluded;

FIG. 8 is the elution temperature-eluted amount curve of a thirdinventive polyethylene composition having a melt index (I₂) ofapproximately 85 g/10 minutes determined by a continuous temperaturerising elution fraction method at equal or above 30° C., wherein thepurge peak which is below 30° C. is excluded and wherein the single peakalso includes artifacts generated due to instrumental noise on the lowtemp side of the peak;

FIG. 9 is the elution temperature-eluted amount curve of a fourthinventive polyethylene composition having a melt index (I₂) ofapproximately 150 g/10 minutes determined by a continuous temperaturerising elution fraction method at equal or above 30° C., wherein thepurge peak which is below 30° C. is excluded; and

FIG. 10 is the elution temperature-eluted amount curve of a fifthinventive polyethylene composition having a melt index (I₂) ofapproximately 200 g/10 minutes determined by a continuous temperaturerising elution fraction method at equal or above 30° C., wherein thepurge peak which is below 30° C. is excluded.

DETAILED DESCRIPTION OF THE INVENTION

The instant invention is a polyethylene composition, method of producingthe same, articles made therefrom, and method of making the same.

The polyethylene composition according to instant invention possessesunique properties and differentiated performance in differentapplications, as described in further details hereinbelow.

The term (co)polymerization, as used herein, refers to thepolymerization of ethylene and optionally one or more comonomers, e.g.one or more α-olefin comonomers. Thus, the term (co)polymerizationrefers to both polymerization of ethylene and copolymerization ofethylene and one or more comonomers, e.g. one or more α-olefincomonomers.

The polyethylene composition according to instant invention has adensity in the range of 0.907 to 0.975 g/cm³. All individual values andsubranges from 0.907 to 0.975 g/cm³ are included herein and disclosedherein; for example, the density can be from a lower limit of 0.907,0.911, 0.919, 0.923, 0.928, or 0.936 g/cm³ to an upper limit of 0.941,0.947, 0.954, 0.959, 0.965, 0.972, or 0.975 g/cm³. For example, thepolyethylene composition may have a density in the range of 0.907 to0.975 g/cm³; or in the alternative, the polyethylene composition mayhave a density in the range of 0.907 to 0.972 g/cm³; or in thealternative, the polyethylene composition may have a density in therange of 0.907 to 0.965 g/cm³; or in the alternative, the polyethylenecomposition may have a density in the range of 0.907 to 0.959 g/cm³; orin the alternative, the polyethylene composition may have a density inthe range of 0.907 to 0.954 g/cm³; or in the alternative, thepolyethylene composition may have a density in the range of 0.907 to0.947 g/cm³; or in the alternative, the polyethylene composition mayhave a density in the range of 0.907 to 0.941 g/cm³; or in thealternative, the polyethylene composition may have a density in therange of 0.911 to 0.972 g/cm³; or in the alternative, the polyethylenecomposition may have a density in the range of 0.940 to 0.975 g/cm³; orin the alternative, the polyethylene composition may have a density inthe range of 0.924 to 0.930 g/cm³; or in the alternative, thepolyethylene composition may have a density in the range of 0.926 to0.936 g/cm³; or in the alternative, the polyethylene composition mayhave a density in the range of 0.940 to 0.946 g/cm³; or in thealternative, the polyethylene composition may have a density in therange of 0.946 to 0.953 g/cm³; or in the alternative, the polyethylenecomposition may have a density in the range of 0.946 to 0.956 g/cm³; orin the alternative, the polyethylene composition may have a density inthe range of 0.948 to 0.956 g/cm³; or in the alternative, thepolyethylene composition may have a density in the range of 0.930 to0.940 g/cm³.

The polyethylene composition according to the instant invention has amolecular weight distribution (M_(w)/M_(n)) (measured according to theconventional GPC method) in the range of 1.70 to 3.62. All individualvalues and subranges from 1.70 to 3.62 are included herein and disclosedherein; for example, the molecular weight distribution (M_(w)/M_(n)) canbe from a lower limit of 1.70, 1.80, 1.90, 2.10, 2.30, 2.50, 2.70, 2.90,3.10, 3.30, or 3.50 to an upper limit of 1.85, 1.95, 2.15, 2.35, 2.55,2.75, 2.95, 3.15, 3.35, 3.55, 3.60, or 3.62. For example, thepolyethylene composition may have a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 3.60; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 3.55; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 3.35; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 3.15; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 2.95; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 2.75; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 2.55; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 2.35; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 2.15; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 1.95; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 1.85.

The polyethylene composition according to the instant invention has amelt index (I₂) in the range of 2 to 1000 g/10 minutes. All individualvalues and subranges from 2 to 1000 g/10 minutes are included herein anddisclosed herein; for example, the melt index (I₂) can be from a lowerlimit of 2, 3, 5, 10, 20, 30, 40, 60, 80, or 100 g/10 minutes, to anupper limit of 10, 30, 50, 80, 90, 110, 200, 220, 250, 300, 500, 800, or1000 g/10 minutes. For example, the polyethylene composition may have amelt index (I₂) in the range of 40 to 80 g/10 minutes; or in thealternative, the polyethylene composition may have a melt index (I₂) inthe range of 80 to 250 g/10 minutes; or in the alternative, thepolyethylene composition may have a melt index (I₂) in the range of 100to 300 g/10 minutes; or in the alternative, the polyethylene compositionmay have a melt index (I₂) in the range of 60 to 110 g/10 minutes; or inthe alternative, the polyethylene composition may have a melt index (I₂)in the range of 30 to 90 g/10 minutes; or in the alternative, thepolyethylene composition may have a melt index (I₂) in the range of 3 to30 g/10 minutes.

The polyethylene composition according to the instant invention has amelt index (I₂₁) in the range of 34 to 24000 g/10 minutes. Allindividual values and subranges from 34 to 24,000 g/10 minutes areincluded herein and disclosed herein; for example, the melt index (I₂₁)can be from a lower limit of 34, 43, 60, 500, 800, 1000, 1200, 1500,1800, or 2000 g/10 minutes, to an upper limit of 24,000, 23,500, 20,000,15,000, 10,000, 9,000, 8,000, 7,000, 6,000, 5,000, 4,000, 3,000, 2,500,2,000, 1,800, 1,000, 800, 700, or 500 g/10 minutes. For example, thepolyethylene composition may have a melt index (I₂₁) in the range of 860to 1880 g/10 minutes; or in the alternative, the polyethylenecomposition may have a melt index (I₂₁) in the range of 1,880 to 5,875g/10 minutes; or in the alternative, the polyethylene composition mayhave a melt index (I₂₁) in the range of 2,150 to 7,050 g/10 minutes; orin the alternative, the polyethylene composition may have a melt index(I₂₁) in the range of 1,290 to 2,585 g/10 minutes; or in thealternative, the polyethylene composition may have a melt index (I₂₁) inthe range of 645 to 2,115 g/10 minutes; or in the alternative, thepolyethylene composition may have a melt index (I₂₁) in the range of64.5 to 705 g/10 minutes.

The polyethylene composition according to the instant invention has amelt flow ratio (I₂₁/I₂) in the range of 17 to 24. All individual valuesand subranges from 17 to 24 minutes are included herein and disclosedherein; for example, the melt flow ratio (I₂₁/I₂) can be from a lowerlimit of 17, 17.5, 18, 18.5, 19, 19.5, 20, 20.5, 21, 21.5, 22, 22.5, or23.5 to an upper limit of 18, 18.5, 19, 19.5, 20, 20.5, 21, 21.5, 22,22.5, 23.5 or 24. For example, the polyethylene composition may have amelt flow ratio (I₂₁/I₂) in the range 17 to 23; or in the alternative,the polyethylene composition may have a melt flow ratio (I₂₁/I₂) in therange 17 to 22; or in the alternative, the polyethylene composition mayhave a melt flow ratio (I₂₁/I₂) in the range 18 to 24; or in thealternative, the polyethylene composition may have a melt flow ratio(I₂₁/I₂) in the range 18 to 23; or in the alternative, the polyethylenecomposition may have a melt flow ratio (I₂₁/I₂) in the range 19 to 24;or in the alternative, the polyethylene composition may have a melt flowratio (I₂₁/I₂) in the range 19 to 23; or in the alternative, thepolyethylene composition may have a melt flow ratio (I₂₁/I₂) in therange 21 to 24; or in the alternative, the polyethylene composition mayhave a melt flow ratio (I₂₁/I₂) in the range 21 to 23.

The polyethylene composition according to the instant invention has amolecular weight (M_(w)) in the range of 15,000 to 100,000 daltons. Allindividual values and subranges from 15,000 to 100,000 daltons areincluded herein and disclosed herein; for example, the molecular weight(M_(w)) can be from a lower limit of 15,000, 20,000, 25,000, 30,000,34,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, or 95,000daltons to an upper limit of 20,000, 25,000, 30,000, 33,000, 40,000,50,000, 60,000, 70,000, 80,000, 90,000, 95,000, 100,000. For example,the polyethylene composition may have a molecular weight (M_(w)) in therange of 15,000 to 100,000 daltons; or in the alternative, thepolyethylene composition may have a molecular weight (M_(w)) in therange of 15,000 to 100,000 daltons; or in the alternative, thepolyethylene composition may have a molecular weight (M_(w)) in therange of 15,000 to 90,000 daltons; or in the alternative, thepolyethylene composition may have a molecular weight (M_(w)) in therange of 20,000 to 80,000 daltons; or in the alternative, thepolyethylene composition may have a molecular weight (M_(w)) in therange of 30,000 to 70,000 daltons; or in the alternative, thepolyethylene composition may have a molecular weight (M_(w)) in therange of 34,000 to 65,000 daltons; or in the alternative, thepolyethylene composition may have a molecular weight (M_(w)) in therange of 15000 to 50,000 daltons; or in the alternative, thepolyethylene composition may have a molecular weight (M_(w)) in therange of 20,000 to 40,000 daltons; or in the alternative, thepolyethylene composition may have a molecular weight (M_(w)) in therange of 20,000 to 33,000 daltons.

The polyethylene composition may have molecular weight distribution(M_(z)/M_(w)) (measured according to the conventional GPC method) in therange of less than 5. All individual values and subranges from less than5 are included herein and disclosed herein; for example, thepolyethylene composition may have a molecular weight distribution(M_(z)/M_(w)) in the range of less than 4.5; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(z)/M_(w)) in the range of less than 4; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(z)/M_(w)) in the range of less than 3.5; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(z)/M_(w)) in the range of less than 3.0; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(z)/M_(w)) in the range of less than 2.8; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(z)/M_(w)) in the range of less than 2.6; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(z)/M_(w)) in the range of less than 2.5; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(z)/M_(w)) in the range of less than 2.4; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(z)/M_(w)) in the range of less than 2.3; or in the alternative, thepolyethylene composition may have a molecular weight distribution(M_(z)/M_(w)) in the range of less than 2.2.

The polyethylene composition may have a vinyl unsaturation of less than0.1 vinyls per one thousand carbon atoms present in the backbone of thepolyethylene composition. All individual values and subranges from lessthan 0.1 are included herein and disclosed herein; for example, thepolyethylene composition may have a vinyl unsaturation of less than 0.08vinyls per one thousand carbon atoms present in the backbone of thepolyethylene composition; or in the alternative, the polyethylenecomposition may have a vinyl unsaturation of less than 0.06 vinyls perone thousand carbon atoms present in the backbone of the polyethylenecomposition; or in the alternative, the polyethylene composition mayhave a vinyl unsaturation of less than 0.04 vinyls per one thousandcarbon atoms present in the backbone of the polyethylene composition; orin the alternative, the polyethylene composition may have a vinylunsaturation of less than 0.02 vinyls per one thousand carbon atomspresent in the backbone of the polyethylene composition; or in thealternative, the polyethylene composition may have a vinyl unsaturationof less than 0.01 vinyls per one thousand carbon atoms present in thebackbone of the polyethylene composition; or in the alternative, thepolyethylene composition may have a vinyl unsaturation of less than0.001 vinyls per one thousand carbon atoms present in the backbone ofthe polyethylene composition.

The polyethylene composition may comprise less than 15 percent by weightof units derived from one or more α-olefin comonomers. All individualvalues and subranges from less than 15 weight percent are includedherein and disclosed herein; for example, the polyethylene compositionmay comprise less than 12 percent by weight of units derived from one ormore α-olefin comonomers; or in the alternative, the polyethylenecomposition may comprise less than 11 percent by weight of units derivedfrom one or more α-olefin comonomers; or in the alternative, thepolyethylene composition may comprise less than 9 percent by weight ofunits derived from one or more α-olefin comonomers; or in thealternative, the polyethylene composition may comprise less than 7percent by weight of units derived from one or more α-olefin comonomers;or in the alternative, the polyethylene composition may comprise lessthan 5 percent by weight of units derived from one or more α-olefincomonomers; or in the alternative, the polyethylene composition maycomprise less than 3 percent by weight of units derived from one or moreα-olefin comonomers; or in the alternative, the polyethylene compositionmay comprise less than 1 percent by weight of units derived from one ormore α-olefin comonomers; or in the alternative, the polyethylenecomposition may comprise less than 0.5 percent by weight of unitsderived from one or more α-olefin comonomers.

The α-olefin comonomers typically have no more than 20 carbon atoms. Forexample, the α-olefin comonomers may preferably have 3 to 10 carbonatoms, and more preferably 3 to 8 carbon atoms. Exemplary α-olefincomonomers include, but are not limited to, propylene, 1-butene,1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and4-methyl-1-pentene. The one or more α-olefin comonomers may, forexample, be selected from the group consisting of propylene, 1-butene,1-hexene, and 1-octene; or in the alternative, from the group consistingof 1-hexene and 1-octene.

The polyethylene composition may comprise at least 85 percent by weightof units derived from ethylene. All individual values and subranges fromat least 85 weight percent are included herein and disclosed herein; forexample, the polyethylene composition may comprise at least 88 percentby weight of units derived from ethylene; or in the alternative, thepolyethylene composition may comprise at least 89 percent by weight ofunits derived from ethylene; or in the alternative, the polyethylenecomposition may comprise at least 91 percent by weight of units derivedfrom ethylene; or in the alternative, the polyethylene composition maycomprise at least 93 percent by weight of units derived from ethylene;or in the alternative, the polyethylene composition may comprise atleast 95 percent by weight of units derived from ethylene; or in thealternative, the polyethylene composition may comprise at least 97percent by weight of units derived from ethylene; or in the alternative,the polyethylene composition may comprise at least 99 percent by weightof units derived from ethylene; or in the alternative, the polyethylenecomposition may comprise at least 99.5 percent by weight of unitsderived from ethylene.

The polyethylene composition of the instant invention is substantiallyfree of any long chain branching, and preferably, the polyethylenecomposition of the instant invention is free of any long chainbranching. Substantially free of any long chain branching, as usedherein, refers to a polyethylene composition preferably substituted withless than about 0.1 long chain branching per 1000 total carbons, andmore preferably, less than about 0.01 long chain branching per 1000total carbons. In the alternative, the polyethylene composition of theinstant invention is free of any long chain branching.

The polyethylene composition may have a short chain branchingdistribution breadth (SCBDB) in the range of 2 to 40° C. All individualvalues and subranges from 2 to 40° C. are included herein and disclosedherein; for example, the short chain branching distribution breadth(SCBDB) can be from a lower limit of 2, 3, 4, 5, 6, 8, 10, 12, 15, 18,20, 25, or 30° C. to an upper limit of 40, 35, 30, 29, 27, 25, 22, 20,15, 12, 10, 8, 6, 4, or 3° C. For example, the polyethylene compositionmay have a short chain branching distribution breadth (SCBDB) in therange of 2 to 35° C.; or in the alternative, the polyethylenecomposition may have a short chain branching distribution breadth(SCBDB) in the range of 2 to 30° C.; or in the alternative, thepolyethylene composition may have a short chain branching distributionbreadth (SCBDB) in the range of 2 to 25° C.; or in the alternative, thepolyethylene composition may have a short chain branching distributionbreadth (SCBDB) in the range of 2 to 20° C.; or in the alternative, thepolyethylene composition may have a short chain branching distributionbreadth (SCBDB) in the range of 2 to 15° C.; or in the alternative, thepolyethylene composition may have a short chain branching distributionbreadth (SCBDB) in the range of 2 to 10° C.; or in the alternative, thepolyethylene composition may have a short chain branching distributionbreadth (SCBDB) in the range of 2 to 5° C.; or in the alternative, thepolyethylene composition may have a short chain branching distributionbreadth (SCBDB) in the range of 4 to 35° C.; or in the alternative, thepolyethylene composition may have a short chain branching distributionbreadth (SCBDB) in the range of 4 to 30° C.; or in the alternative, thepolyethylene composition may have a short chain branching distributionbreadth (SCBDB) in the range of 4 to 25° C.; or in the alternative, thepolyethylene composition may have a short chain branching distributionbreadth (SCBDB) in the range of 4 to 20° C.; or in the alternative, thepolyethylene composition may have a short chain branching distributionbreadth (SCBDB) in the range of 4 to 15° C.; or in the alternative, thepolyethylene composition may have a short chain branching distributionbreadth (SCBDB) in the range of 4 to 10° C.; or in the alternative, thepolyethylene composition may have a short chain branching distributionbreadth (SCBDB) in the range of 4 to 5° C. Referring to FIG. 1, thepolyethylene composition in accordance with the instant invention mayhave a short chain branching distribution breadth (SCBDB) expressed in °C. of less than or equal to [0.0312 (I₂)+2.87], wherein I₂ is melt indexexpressed in g/10 min, and wherein the polyethylene composition has adensity in the range of equal or greater than 0.940 g/cm³, for example,0.940 to 0.975 g/cm³. Referring to FIG. 2, in the alternative, thepolyethylene composition in accordance with the instant invention mayhave a short chain branching distribution breadth (SCBDB) expressed in °C. of less than or equal to [0.025 (I₂)+4.08], wherein I₂ is melt indexexpressed in g/10 min, and wherein the polyethylene composition has adensity in the range of equal or greater than 0.930 g/cm³ to less than0.940 g/cm³.

The polyethylene composition in accordance with the instant inventionmay further have any tensile impact strength expressed in ft-lb/in². Forexample, the polyethylene composition in accordance with the instantinvention may have a tensile impact strength in the range of 5 to 120ft-lb/in². All individual values and subranges from 5 to 120 ft-lb/in²are included herein and disclosed herein; for example, the tensileimpact strength can be from a lower limit of 5, 10, 15, 20, 25, 30, 35,40, or 45 ft-lb/in² to an upper limit of 20, 30, 40, 50, 60, 70, 80, 90,100, 110, or 120 ft-lb/in². For example, the inventive polyethylenecomposition may have a tensile impact strength in the range of 5 to 90ft-lb/in²; or in the alternative, the inventive polyethylene compositionmay have a tensile impact strength in the range of 5 to 50 ft-lb/in²; orin the alternative, the inventive polyethylene composition may have atensile impact strength in the range of 5 to 40 ft-lb/in²; or in thealternative, the inventive polyethylene composition may have a tensileimpact strength in the range of 5 to 30 ft-lb/in²; or in thealternative, the inventive polyethylene composition may have a tensileimpact strength in the range of 5 to 20 ft-lb/in²; or in thealternative, the inventive polyethylene composition may have a tensileimpact strength in the range of 10 to 50 ft-lb/in²; or in thealternative, the inventive polyethylene composition may have a tensileimpact strength in the range of 10 to 40 ft-lb/in²; or in thealternative, the inventive polyethylene composition may have a tensileimpact strength in the range of 10 to 30 ft-lb/in²; or in thealternative, the inventive polyethylene composition may have a tensileimpact strength in the range of 10 to 20 ft-lb/in²; or in thealternative, the inventive polyethylene composition may have a tensileimpact strength in the range of 20 to 50 ft-lb/in²; or in thealternative, the inventive polyethylene composition may have a tensileimpact strength in the range of 20 to 40 ft-lb/in²; or in thealternative, the inventive polyethylene composition may have a tensileimpact strength in the range of 20 to 35 ft-lb/in²; or in thealternative, the inventive polyethylene composition may have a tensileimpact strength in the range of 20 to 30 ft-lb/in²; or in thealternative, the inventive polyethylene composition may have a tensileimpact strength in the range of 15 to 5 ft-lb/int.

The polyethylene composition may have a shear viscosity in the range of20 to 250 Pascal-s at 3000 s⁻¹ shear rate measured at 190° C. Allindividual values and subranges from 20 to 250 Pascal-s at 3000 s⁻¹shear rate measured at 190° C. are included herein and disclosed herein;for example, the polyethylene composition may have a shear viscosity inthe range of 20 to 200 Pascal-s at 3000 s⁻¹ shear rate measured at 190°C.; or in the alternative, the polyethylene composition may have a shearviscosity in the range of 20 to 150 Pascal-s at 3000 s⁻¹ shear ratemeasured at 190° C.; or in the alternative, the polyethylene compositionmay have a shear viscosity in the range of 20 to 130 Pascal-s at 3000s⁻¹ shear rate measured at 190° C.; or in the alternative, thepolyethylene composition may have a shear viscosity in the range of 25to 150 Pascal-s at 3000 s⁻¹ shear rate measured at 190° C.; or in thealternative, the polyethylene composition may have a shear viscosity inthe range of 25 to 80 Pascal-s at 3000 s⁻¹ shear rate measured at 190°C.; or in the alternative, the polyethylene composition may have a shearviscosity in the range of 25 to 55 Pascal-s at 3000 s⁻¹ shear ratemeasured at 190° C.; or in the alternative, the polyethylene compositionmay have a shear viscosity in the range of 25 to 50 Pascal-s at 3000 s⁻¹shear rate measured at 190° C.; or in the alternative, the polyethylenecomposition may have a shear viscosity in the range of 25 to 45 Pascal-sat 3000 s⁻¹ shear rate measured at 190° C.; or in the alternative, thepolyethylene composition may have a shear viscosity in the range of 25to 45 Pascal-s at 3000 s⁻¹ shear rate measured at 190° C.; or in thealternative, the polyethylene composition may have a shear viscosity inthe range of 25 to 35 Pascal-s at 3000 s⁻¹ shear rate measured at 190°C.; or in the alternative, the polyethylene composition may have a shearviscosity in the range of 25 to 30 Pascal-s at 3000 s⁻¹ shear ratemeasured at 190° C.; or in the alternative, the polyethylene compositionmay have a shear viscosity in the range of 30 to 55 Pascal-s at 3000 s⁻¹shear rate measured at 190° C.; or in the alternative, the polyethylenecomposition may have a shear viscosity in the range of 35 to 55 Pascal-sat 3000 s⁻¹ shear rate measured at 190° C.; or in the alternative, thepolyethylene composition may have a shear viscosity in the range of 40to 55 Pascal-s at 3000 s⁻¹ shear rate measured at 190° C.; or in thealternative, the polyethylene composition may have a shear viscosity inthe range of 45 to 55 Pascal-s at 3000 s⁻¹ shear rate measured at 190°C.; or in the alternative, the polyethylene composition may have a shearviscosity in the range of 50 to 55 Pascal-s at 3000 s⁻¹ shear ratemeasured at 190° C.

The polyethylene composition may further have a 1% secant modulus in therange of 65,000 to 250,000 psi. All individual values and subranges from65,000 to 250,000 psi are included herein and disclosed herein; forexample, the 1% secant modulus can be from a lower limit of 65,000,75,000, 80,000, 85,000, 90,000, 100,000, or 120,000 psi to an upperlimit of 250,000, 220,000, 200,000, 150,000, 140,000, 130,000, 115,000,110,000, 105,000, 100,000, 95,000, 90,000, 85,000, or 80,000. Forexample, the polyethylene composition may have a 1% secant modulus inthe range of 65,000 to 200,000 psi; or in the alternative, thepolyethylene composition may have a 1% secant modulus in the range of65,000 to 150,000 psi; or in the alternative, the polyethylenecomposition may have a 1% secant modulus in the range of 65,000 to140,000 psi; or in the alternative, the polyethylene composition mayhave a 1% secant modulus in the range of 65,000 to 120,000 psi; or inthe alternative, the polyethylene composition may have a 1% secantmodulus in the range of 65,000 to 115,000 psi; or in the alternative,the polyethylene composition may have a 1% secant modulus in the rangeof 150,000 to 200,000 psi; or in the alternative, the polyethylenecomposition may have a 1% secant modulus in the range of 75,000 to110,000 psi; or in the alternative, the polyethylene composition mayhave a 1% secant modulus in the range of 75,000 to 100,000 psi; or inthe alternative, the polyethylene composition may have a 1% secantmodulus in the range of 75,000 to 95,000 psi; or in the alternative, thepolyethylene composition may have a 1% secant modulus in the range of75,000 to 90,000 psi; or in the alternative, the polyethylenecomposition may have a 1% secant modulus in the range of 80,000 to95,000 psi; or in the alternative, the polyethylene composition may havea 1% secant modulus in the range of 80,000 to 90,000 psi.

In one embodiment, the polyethylene composition in accordance with theinstant invention may have a tensile impact strength expressed inft-lb/in² of equal or greater than[(−6.53*10⁻⁵)(x⁴)]+[(1.3*10⁻²)(x³)]−[(9.68*10⁻¹)(x²)]+[(3.22*10)(x)]−[(3.69*10²)],wherein x is the shear viscosity of the polyethylene compositionexpressed in Pascal-s at 3000 s⁻¹ shear rate measured at 190° C. Inanother embodiment, the inventive polyethylene composition may have atensile impact strength expressed in ft-lb/in² of equal or greater than[(−6.53*10⁻⁵)(x⁴)]+[(1.3*10⁻²)(x³)]−[(9.68*10⁻¹)(x²)]+[(3.22*10)(x)]−[(3.69*10²)],wherein x is the shear viscosity of the polyethylene composition in therange of 25 to 55 expressed in Pascal-s at 3000 s⁻¹ shear rate measuredat 190° C. In another embodiment, the inventive polyethylene compositionmay have a tensile impact strength expressed in ft-lb/in² of equal orgreater than[(−6.53*10⁻⁵)(x⁴)]+[(1.3*10⁻²)(x³)]−[(9.68*10⁻¹)(x²)]+[(3.22*10)(x)]−[(3.69*10²)],wherein x is the shear viscosity of the polyethylene composition in therange of 25 to 55 expressed in Pascal-s at 3000 s⁻¹ shear rate measuredat 190° C., and wherein the inventive polyethylene composition has a 1%secant modulus in the range of 75,000 to 115,000 psi. In anotherembodiment, the inventive polyethylene composition may have a tensileimpact strength expressed in ft-lb/in² of equal or greater than[(−6.53*10⁻⁵)(x⁴)]+[(1.3*10⁻²)(x³)]−[(9.68*10⁻¹)(x²)]+[(3.22*10)(x)]−[(3.69*10²)],wherein x is the shear viscosity of the polyethylene compositionexpressed in Pascal-s at 3000 s⁻¹ shear rate measured at 190° C., andwherein the inventive polyethylene composition has a 1% secant modulusin the range of 75,000 to 115,000 psi. In another embodiment, theinventive polyethylene composition may have a tensile impact strengthexpressed in ft-lb/in² of equal or greater than[(−6.53*10⁻⁵)(x⁴)]+[(1.3*10⁻²)(x³)]−[(9.68*10⁻¹)(x²)]+[(3.22*10)(x)]−[(3.69*10²)],wherein x is the shear viscosity of the polyethylene compositionexpressed in Pascal-s at 3000 s⁻¹ shear rate measured at 190° C., andwherein the inventive polyethylene composition has a 1% secant modulusin the range of 75,000 to 110,000 psi. In another alternativeembodiment, the inventive polyethylene composition may have a tensileimpact strength expressed in ft-lb/in² of equal or greater than[(−6.53*10⁻⁵)(x⁴)]+[(1.3*10⁻²)(x³)]−[(9.68*10⁻¹)(x²)]+[(3.22*10)(x)]−[(3.69*10²)],wherein x is the shear viscosity of the polyethylene compositionexpressed in Pascal-s at 3000 s⁻¹ shear rate measured at 190° C., andwherein the inventive polyethylene composition has a 1% secant modulusin the range of 75,000 to 100,000 psi. In another alternativeembodiment, the inventive polyethylene composition may have a tensileimpact strength expressed in ft-lb/in² of equal or greater than[(−6.53*10⁻⁵)(x⁴)]+[(1.3*10⁻²)(x³)]−[(9.68*10¹)(x²)]+[(3.22*10)(x)]−[(3.69*10²)],wherein x is the shear viscosity of the polyethylene compositionexpressed in Pascal-s at 3000 s⁻¹ shear rate measured at 190° C., andwherein the inventive polyethylene composition has a 1% secant modulusin the range of 75,000 to 95,000 psi. In another alternative embodiment,the inventive polyethylene composition may have a tensile impactstrength expressed in ft-lb/in² of equal or greater than[(−6.53*10⁻⁵)(x⁴)]+[(1.3*10⁻²)(x³)]−[(9.68*10⁻¹)(x²)]+[(3.22*10)(x)]−[(3.69*10²)],wherein x is the shear viscosity of the polyethylene compositionexpressed in Pascal-s at 3000 s⁻¹ shear rate measured at 190° C., andwherein the inventive polyethylene composition has a 1% secant modulusin the range of 75,000 to 90,000 psi. In another alternative embodiment,the inventive polyethylene composition may have a tensile impactstrength expressed in ft-lb/in² of equal or greater than[(−6.53*10⁻⁵)(x⁴)]+[(1.3*10⁻²)(x³)]−[(9.68*10¹)(x²)]+[(3.22*10)(x)]−[(3.69*10²)],wherein x is the shear viscosity of the polyethylene compositionexpressed in Pascal-s at 3000 s⁻¹ shear rate measured at 190° C., andwherein the inventive polyethylene composition has a 1% secant modulusin the range of 80,000 to 95,000 psi. In another alternative embodiment,the inventive polyethylene composition may have a tensile impactstrength expressed in ft-lb/in² of equal or greater than[(−6.53*10⁻⁵)(x⁴)]+[(1.3*10⁻²)(x³)]−[(9.68*10⁻¹)(x²)]+[(3.22*10)(x)]−[(3.69*10²)],wherein x is the shear viscosity of the polyethylene compositionexpressed in Pascal-s at 3000 s⁻¹ shear rate measured at 190° C., andwherein the inventive polyethylene composition has a 1% secant modulusin the range of 80,000 to 100,000 psi.

The polyethylene composition may further comprise less than or equal to100 parts by weight of hafnium residues remaining from the hafnium basedmetallocene catalyst per one million parts of polyethylene composition.All individual values and subranges from less than or equal to 100 ppmare included herein and disclosed herein; for example, the polyethylenecomposition may further comprise less than or equal to 10 parts byweight of hafnium residues remaining from the hafnium based metallocenecatalyst per one million parts of polyethylene composition; or in thealternative, the polyethylene composition may further comprise less thanor equal to 8 parts by weight of hafnium residues remaining from thehafnium based metallocene catalyst per one million parts of polyethylenecomposition; or in the alternative, the polyethylene composition mayfurther comprise less than or equal to 6 parts by weight of hafniumresidues remaining from the hafnium based metallocene catalyst per onemillion parts of polyethylene composition; or in the alternative, thepolyethylene composition may further comprise less than or equal to 4parts by weight of hafnium residues remaining from the hafnium basedmetallocene catalyst per one million parts of polyethylene composition;or in the alternative, the polyethylene composition may further compriseless than or equal to 2 parts by weight of hafnium residues remainingfrom the hafnium based metallocene catalyst per one million parts ofpolyethylene composition; or in the alternative, the polyethylenecomposition may further comprise less than or equal to 1.5 parts byweight of hafnium residues remaining from the hafnium based metallocenecatalyst per one million parts of polyethylene composition; or in thealternative, the polyethylene composition may further comprise less thanor equal to 1 parts by weight of hafnium residues remaining from thehafnium based metallocene catalyst per one million parts of polyethylenecomposition; or in the alternative, the polyethylene composition mayfurther comprise less than or equal to 0.75 parts by weight of hafniumresidues remaining from the hafnium based metallocene catalyst per onemillion parts of polyethylene composition; or in the alternative, thepolyethylene composition may further comprise less than or equal to 0.5parts by weight of hafnium residues remaining from the hafnium basedmetallocene catalyst per one million parts of polyethylene compositionthe polyethylene composition may further comprise less than or equal to0.25 parts by weight of hafnium residues remaining from the hafniumbased metallocene catalyst per one million parts of polyethylenecomposition. The hafnium residues remaining from the hafnium basedmetallocene catalyst in the inventive polyethylene composition may bemeasured by x-ray fluorescence (XRF), which is calibrated to referencestandards. The polymer resin granules were compression molded atelevated temperature into plaques having a thickness of about ⅜ of aninch for the x-ray measurement in a preferred method. At very lowconcentrations of metal, such as below 0.1 ppm, ICP-AES would be asuitable method to determine metal residues present in the inventivepolyethylene composition. In one embodiment, the inventive polyethylenecomposition has substantially no chromium, zirconium or titaniumcontent, that is, no or only what would be considered by those skilledin the art, trace amounts of these metals are present, such as, forexample, less than 0.001 ppm.

The polyethylene composition in accordance with the instant inventionmay have less than 2 peaks on an elution temperature-eluted amount curvedetermined by continuous temperature rising elution fraction method atequal or above 30° C., wherein the purge peak which is below 30° C. isexcluded. In the alternative, the polyethylene composition may have only1 peak or less on an elution temperature-eluted amount curve determinedby continuous temperature rising elution fraction method at equal orabove 30° C., wherein the purge peak which is below 30° C. is excluded.In the alternative, the polyethylene composition may have only 1 peak onan elution temperature-eluted amount curve determined by continuoustemperature rising elution fraction method at equal or above 30° C.,wherein the purge peak which is below 30° C. is excluded. In addition,artifacts generated due to instrumental noise at either side of a peakare not considered to be peaks.

The inventive polyethylene composition may further comprise additionalcomponents such as other polymers and/or additives. Such additivesinclude, but are not limited to, antistatic agents, color enhancers,dyes, lubricants, fillers, pigments, primary antioxidants, secondaryantioxidants, processing aids, UV stabilizers, and combinations thereof.The inventive polyethylene composition may contain any amounts ofadditives. The inventive polyethylene composition may comprise fromabout 0 to about 10 percent by the combined weight of such additives,based on the weight of the inventive polyethylene composition includingsuch additives. All individual values and subranges from about 0 toabout 10 weight percent are included herein and disclosed herein; forexample, the inventive polyethylene composition may comprise from 0 to 7percent by the combined weight of additives, based on the weight of theinventive polyethylene composition including such additives; in thealternative, the inventive polyethylene composition may comprise from 0to 5 percent by the combined weight of additives, based on the weight ofthe inventive polyethylene composition including such additives; or inthe alternative, the inventive polyethylene composition may comprisefrom 0 to 3 percent by the combined weight of additives, based on theweight of the inventive polyethylene composition including suchadditives; or in the alternative, the inventive polyethylene compositionmay comprise from 0 to 2 percent by the combined weight of additives,based on the weight of the inventive polyethylene composition includingsuch additives; or in the alternative, the inventive polyethylenecomposition may comprise from 0 to 1 percent by the combined weight ofadditives, based on the weight of the inventive polyethylene compositionincluding such additives; or in the alternative, the inventivepolyethylene composition may comprise from 0 to 0.5 percent by thecombined weight of additives, based on the weight of the inventivepolyethylene composition including such additives. Antioxidants, such asIrgafos™ 168 and Irganox™ 1010, may be used to protect the inventivepolyethylene composition from thermal and/or oxidative degradation.Irganox™ 1010 is tetrakis (methylene(3,5-di-tert-butyl-4hydroxyhydrocinnamate) available from Ciba GeigyInc. Irgafos™ 168 is tris (2,4 di-tert-butylphenyl) phosphite availablefrom Ciba Geigy Inc.

Any conventional ethylene (co)polymerization reaction may be employed toproduce the inventive polyethylene composition. Such conventionalethylene (co)polymerization reactions include, but are not limited to,gas phase polymerization process, slurry phase polymerization process,liquid phase polymerization process, and combinations thereof using oneor more conventional reactors, e.g. fluidized bed gas phase reactors,loop reactors, stirred tank reactors, batch reactors in parallel,series, and/or any combinations thereof. In the alternative, theinventive polyethylene composition may be produced in a high pressurereactor via a coordination catalyst system. For example, the inventivepolyethylene composition according to the instant invention may beproduced via gas phase polymerization process in a single gas phasereactor; however, the instant invention is not so limited, and any ofthe above polymerization processes may be employed. In one embodiment,the polymerization reactor may comprise of two or more reactors inseries, parallel, or combinations thereof. Preferably, thepolymerization reactor is one reactor, e.g. a fluidized bed gas phasereactor. In another embodiment, the gas phase polymerization reactor isa continuous polymerization reactor comprising one or more feed streams.In the polymerization reactor, the one or more feed streams are combinedtogether, and the gas comprising ethylene and optionally one or morecomonomers, e.g. one or more α-olefins, are flowed or cycledcontinuously through the polymerization reactor by any suitable means.The gas comprising ethylene and optionally one or more comonomers, e.g.one or more α-olefins, may be fed up through a distributor plate tofluidize the bed in a continuous fluidization process.

In production, a hafnium based metallocene catalyst system including acocatalyst, as described hereinbelow in further details, ethylene,optionally one or more alpha-olefin comonomers, hydrogen, optionally oneor more inert gases and/or liquids, e.g. N₂, isopentane, and hexane, andoptionally one or more continuity additive, e.g. ethoxylated stearylamine or aluminum distearate or combinations thereof, are continuouslyfed into a reactor, e.g. a fluidized bed gas phase reactor. The reactormay be in fluid communication with one or more discharge tanks, surgetanks, purge tanks, and/or recycle compressors. The temperature in thereactor is typically in the range of 70 to 115° C., preferably 75 to110° C., more preferably 75 to 100° C., and the pressure is in the rangeof 15 to 30 atm, preferably 17 to 26 atm. A distributor plate at thebottom of the polymer bed provides a uniform flow of the upflowingmonomer, comonomer, and inert gases stream. A mechanical agitator mayalso be provided to provide contact between the solid particles and thecomonomer gas stream. The fluidized bed, a vertical cylindrical reactor,may have a bulb shape at the top to facilitate the reduction of gasvelocity; thus, permitting the granular polymer to separate from theupflowing gases. The unreacted gases are then cooled to remove the heatof polymerization, recompressed, and then recycled to the bottom of thereactor. Once the residual hydrocarbons are removed, and the resin istransported under N₂ to a purge bin, moisture may be introduced toreduce the presence of any residual catalyzed reactions with O₂ beforethe inventive polyethylene composition is exposed to oxygen. Theinventive polyethylene composition may then be transferred to anextruder to be pelletized. Such pelletization techniques are generallyknown. The inventive polyethylene composition may further be meltscreened. Subsequent to the melting process in the extruder, the moltencomposition is passed through one or more active screens, positioned inseries of more than one, with each active screen having a micronretention size of from about 2 μm to about 400 μm (2 to 4×10⁻⁵ m), andpreferably about 2 μm to about 300 μm (2 to 3×10⁻⁵ m), and mostpreferably about 2 μm to about 70 μm (2 to 7×10⁻⁶ m), at a mass flux ofabout 5 to about 100 lb/hr/in² (1.0 to about 20 kg/s/m²). Such furthermelt screening is disclosed in U.S. Pat. No. 6,485,662, which isincorporated herein by reference to the extent that it discloses meltscreening.

In an embodiment of a fluidized bed reactor, a monomer stream is passedto a polymerization section. The fluidized bed reactor may include areaction zone in fluid communication with a velocity reduction zone. Thereaction zone includes a bed of growing polymer particles, formedpolymer particles and catalyst composition particles fluidized by thecontinuous flow of polymerizable and modifying gaseous components in theform of make-up feed and recycle fluid through the reaction zone.Preferably, the make-up feed includes polymerizable monomer, mostpreferably ethylene and optionally one or more α-olefin comonomers, andmay also include condensing agents as is known in the art and disclosedin, for example, U.S. Pat. No. 4,543,399, U.S. Pat. No. 5,405,922, andU.S. Pat. No. 5,462,999.

The fluidized bed has the general appearance of a dense mass ofindividually moving particles, preferably polyethylene particles, ascreated by the percolation of gas through the bed. The pressure dropthrough the bed is equal to or slightly greater than the weight of thebed divided by the cross-sectional area. It is thus dependent on thegeometry of the reactor. To maintain a viable fluidized bed in thereaction zone, the superficial gas velocity through the bed must exceedthe minimum flow required for fluidization. Preferably, the superficialgas velocity is at least two times the minimum flow velocity.Ordinarily, the superficial gas velocity does not exceed 1.5 m/sec andusually no more than 0.76 ft/sec is sufficient.

In general, the height to diameter ratio of the reaction zone can varyin the range of about 2:1 to about 5:1. The range, of course, can varyto larger or smaller ratios and depends upon the desired productioncapacity. The cross-sectional area of the velocity reduction zone istypically within the range of about 2 to about 3 multiplied by thecross-sectional area of the reaction zone.

The velocity reduction zone has a larger inner diameter than thereaction zone, and can be conically tapered in shape. As the namesuggests, the velocity reduction zone slows the velocity of the gas dueto the increased cross sectional area. This reduction in gas velocitydrops the entrained particles into the bed, reducing the quantity ofentrained particles that flow from the reactor. The gas exiting theoverhead of the reactor is the recycle gas stream.

The recycle stream is compressed in a compressor and then passed througha heat exchange zone where heat is removed before the stream is returnedto the bed. The heat exchange zone is typically a heat exchanger, whichcan be of the horizontal or vertical type. If desired, several heatexchangers can be employed to lower the temperature of the cycle gasstream in stages. It is also possible to locate the compressordownstream from the heat exchanger or at an intermediate point betweenseveral heat exchangers. After cooling, the recycle stream is returnedto the reactor through a recycle inlet line. The cooled recycle streamabsorbs the heat of reaction generated by the polymerization reaction.

Preferably, the recycle stream is returned to the reactor and to thefluidized bed through a gas distributor plate. A gas deflector ispreferably installed at the inlet to the reactor to prevent containedpolymer particles from settling out and agglomerating into a solid massand to prevent liquid accumulation at the bottom of the reactor as wellto facilitate easy transitions between processes that contain liquid inthe cycle gas stream and those that do not and vice versa. Suchdeflectors are described in the U.S. Pat. No. 4,933,149 and U.S. Pat.No. 6,627,713.

The hafnium based catalyst system used in the fluidized bed ispreferably stored for service in a reservoir under a blanket of a gas,which is inert to the stored material, such as nitrogen or argon. Thehafnium based catalyst system may be added to the reaction system, orreactor, at any point and by any suitable means, and is preferably addedto the reaction system either directly into the fluidized bed ordownstream of the last heat exchanger, i.e. the exchanger farthestdownstream relative to the flow, in the recycle line, in which case theactivator is fed into the bed or recycle line from a dispenser. Thehafnium based catalyst system is injected into the bed at a point abovedistributor plate. Preferably, the hafnium based catalyst system isinjected at a point in the bed where good mixing with polymer particlesoccurs. Injecting the hafnium based catalyst system at a point above thedistribution plate facilitates the operation of a fluidized bedpolymerization reactor.

The monomers can be introduced into the polymerization zone in variousways including, but not limited to, direct injection through a nozzleinto the bed or cycle gas line. The monomers can also be sprayed ontothe top of the bed through a nozzle positioned above the bed, which mayaid in eliminating some carryover of fines by the cycle gas stream.

Make-up fluid may be fed to the bed through a separate line to thereactor. The composition of the make-up stream is determined by a gasanalyzer. The gas analyzer determines the composition of the recyclestream, and the composition of the make-up stream is adjustedaccordingly to maintain an essentially steady state gaseous compositionwithin the reaction zone. The gas analyzer can be a conventional gasanalyzer that determines the recycle stream composition to maintain theratios of feed stream components. Such equipment is commerciallyavailable from a wide variety of sources. The gas analyzer is typicallypositioned to receive gas from a sampling point located between thevelocity reduction zone and heat exchanger.

The production rate of inventive polyethylene composition may beconveniently controlled by adjusting the rate of catalyst compositioninjection, activator injection, or both. Since any change in the rate ofcatalyst composition injection will change the reaction rate and thusthe rate at which heat is generated in the bed, the temperature of therecycle stream entering the reactor is adjusted to accommodate anychange in the rate of heat generation. This ensures the maintenance ofan essentially constant temperature in the bed. Complete instrumentationof both the fluidized bed and the recycle stream cooling system is, ofcourse, useful to detect any temperature change in the bed so as toenable either the operator or a conventional automatic control system tomake a suitable adjustment in the temperature of the recycle stream.

Under a given set of operating conditions, the fluidized bed ismaintained at essentially a constant height by withdrawing a portion ofthe bed as product at the rate of formation of the particulate polymerproduct. Since the rate of heat generation is directly related to therate of product formation, a measurement of the temperature rise of thefluid across the reactor, i.e. the difference between inlet fluidtemperature and exit fluid temperature, is indicative of the rate ofinventive polyethylene composition formation at a constant fluidvelocity if no or negligible vaporizable liquid is present in the inletfluid.

On discharge of particulate polymer product from reactor, it isdesirable and preferable to separate fluid from the product and toreturn the fluid to the recycle line. There are numerous ways known tothe art to accomplish this separation. Product discharge systems whichmay be alternatively employed are disclosed and claimed in U.S. Pat. No.4,621,952. Such a system typically employs at least one (parallel) pairof tanks comprising a settling tank and a transfer tank arranged inseries and having the separated gas phase returned from the top of thesettling tank to a point in the reactor near the top of the fluidizedbed.

In the fluidized bed gas phase reactor embodiment, the reactortemperature of the fluidized bed process herein ranges from 70° C. or75° C., or 80° C. to 90° C. or 95° C. or 100° C. or 110° C. or 115° C.,wherein a desirable temperature range comprises any upper temperaturelimit combined with any lower temperature limit described herein. Ingeneral, the reactor temperature is operated at the highest temperaturethat is feasible, taking into account the sintering temperature of theinventive polyethylene composition within the reactor and fouling thatmay occur in the reactor or recycle line(s).

The process of the present invention is suitable for the production ofhomopolymers comprising ethylene derived units, or copolymers comprisingethylene derived units and at least one or more other α-olefin(s)derived units.

In order to maintain an adequate catalyst productivity in the presentinvention, it is preferable that the ethylene is present in the reactorat a partial pressure at or greater than 160 psia (1100 kPa), or 190psia (1300 kPa), or 200 psia (1380 kPa), or 210 psia (1450 kPa), or 220psia (1515 kPa).

The comonomer, e.g. one or more α-olefin comonomers, if present in thepolymerization reactor, is present at any level that will achieve thedesired weight percent incorporation of the comonomer into the finishedpolyethylene. This is expressed as a mole ratio of comonomer to ethyleneas described herein, which is the ratio of the gas concentration ofcomonomer moles in the cycle gas to the gas concentration of ethylenemoles in the cycle gas. In one embodiment of the inventive polyethylenecomposition production, the comonomer is present with ethylene in thecycle gas in a mole ratio range of from 0 to 0.1 (comonomer:ethylene);and from 0 to 0.05 in another embodiment; and from 0 to 0.04 in anotherembodiment; and from 0 to 0.03 in another embodiment; and from 0 to 0.02in another embodiment.

Hydrogen gas may also be added to the polymerization reactor(s) tocontrol the final properties (e.g., I₂₁ and/or I₂) of the inventivepolyethylene composition. In one embodiment, the ratio of hydrogen tototal ethylene monomer (ppm H₂/mol % C₂) in the circulating gas streamis in a range of from 0 to 60:1 in one embodiment; from 0.10:1 (0.10) to50:1 (50) in another embodiment; from 0 to 35:1 (35) in anotherembodiment; from 0 to 25:1 (25) in another embodiment; from 7:1 (7) to22:1 (22).

In one embodiment, the process for producing a polyethylene compositionaccording to the instant invention comprises the steps of: (1)(co)polymerizing ethylene and optionally one or more α-olefin comonomerin the presence of a hafnium based metallocene catalyst via a gas phase(co)polymerization process in a single stage reactor; and (2) therebyproducing the inventive polyethylene composition, wherein thepolyethylene composition has a density in the range of 0.907 to 0.975g/cm³, a molecular weight distribution (M_(w)/M_(n)) in the range of1.70 to 3.62, a melt index (I₂) in the range of 2 to 1000 g/10 minutes,a molecular weight distribution (M_(z)/M_(w)) in the range of less than2.5, and a vinyl unsaturation of less than 0.06 vinyls per one thousandcarbon atoms present in the backbone of the composition.

In one embodiment, the process for producing a polyethylene compositionaccording to the instant invention comprises the steps of: (1)(co)polymerizing ethylene and optionally one or more α-olefin comonomerin the presence of a hafnium based metallocene catalyst via a gas phase(co)polymerization process in a single stage reactor; and (2) therebyproducing the inventive polyethylene composition, wherein thepolyethylene composition has a density in the range of 0.950 to 0.954g/cm³, a molecular weight distribution (M_(w)/M_(n)) in the range of 2.9to 3.5, a melt index (I₂) in the range of 34 to 46 g/10 minutes, amolecular weight distribution (M_(z)/M_(w)) in the range of less than2.2, and a vinyl unsaturation of less than 0.01 vinyls per one thousandcarbon atoms present in the backbone of the composition.

In one embodiment, the process for producing a polyethylene compositionaccording to the instant invention comprises the steps of: (1)(co)polymerizing ethylene and optionally one or more α-olefin comonomerin the presence of a hafnium based metallocene catalyst via a gas phase(co)polymerization process in a single stage reactor; and (2) therebyproducing the inventive polyethylene composition, wherein thepolyethylene composition has a density in the range of 0.950 to 0.954g/cm³, a molecular weight distribution (M_(w)/M_(n)) in the range of 2.7to 3.3, a melt index (I₂) in the range of 68 to 92 g/10 minutes, amolecular weight distribution (M_(w)/M_(n)) in the range of less than2.2, and a vinyl unsaturation of less than 0.01 vinyls per one thousandcarbon atoms present in the backbone of the composition.

The hafnium based catalyst system, as used herein, refers to a catalystcapable of catalyzing the polymerization of ethylene monomers andoptionally one or more α-olefin co monomers to produce polyethylene.Furthermore, the hafnium based catalyst system comprises a hafnocenecomponent. The hafnocene component may comprise mono-, bis- ortris-cyclopentadienyl-type complexes of hafnium. In one embodiment, thecyclopentadienyl-type ligand comprises cyclopentadienyl or ligandsisolobal to cyclopentadienyl and substituted versions thereof.Representative examples of ligands isolobal to cyclopentadienyl include,but are not limited to, cyclopentaphenanthreneyl, indenyl, benzindenyl,fluorenyl, octahydrofluorenyl, cyclooctatetraenyl,cyclopentacyclododecene, phenanthrindenyl, 3,4-benzofluorenyl,9-phenylfluorenyl, 8-H-cyclopent[a]acenaphthylenyl, 7H-dibenzofluorenyl,indeno[1,2-9]anthrene, thiophenoindenyl, thiophenofluorenyl,hydrogenated versions thereof (e.g., 4,5,6,7-tetrahydroindenyl, or“H₄Ind”) and substituted versions thereof. In one embodiment, thehafnocene component is an unbridged bis-cyclopentadienyl hafnocene andsubstituted versions thereof. In another embodiment, the hafnocenecomponent excludes unsubstituted bridged and unbridgedbis-cyclopentadienyl hafnocenes, and unsubstituted bridged and unbridgedbis-indenyl hafnocenes. The term “unsubstituted,” as used herein, meansthat there are only hydride groups bound to the rings and no othergroup. Preferably, the hafnocene useful in the present invention can berepresented by the formula (where “Hf” is hafnium):

Cp_(n)HfX_(p)  (1)

wherein n is 1 or 2, p is 1, 2 or 3, each Cp is independently acyclopentadienyl ligand or a ligand isolobal to cyclopentadienyl or asubstituted version thereof bound to the hafnium; and X is selected fromthe group consisting of hydride, halides, C₁ to C₁₀ alkyls and C₂ to C₁₂alkenyls; and wherein when n is 2, each Cp may be bound to one anotherthrough a bridging group A selected from the group consisting of C₁ toC₅ alkylenes, oxygen, alkylamine, silyl-hydrocarbons, andsiloxyl-hydrocarbons. An example of C₁ to C₅ alkylenes include ethylene(—CH₂CH₂—) bridge groups; an example of an alkylamine bridging groupincludes methylamide (—(CH₃)N—); an example of a silyl-hydrocarbonbridging group includes dimethylsilyl (—(CH₃)₂Si—); and an example of asiloxyl-hydrocarbon bridging group includes (—O—(CH₃)₂Si—O—). In oneparticular embodiment, the hafnocene component is represented by formula(1), wherein n is 2 and p is 1 or 2.

As used herein, the term “substituted” means that the referenced grouppossesses at least one moiety in place of one or more hydrogens in anyposition, the moieties selected from such groups as halogen radicalssuch as F, Cl, Br., hydroxyl groups, carbonyl groups, carboxyl groups,amine groups, phosphine groups, alkoxy groups, phenyl groups, naphthylgroups, C₁ to C₁₀ alkyl groups, C₂ to C₁₀ alkenyl groups, andcombinations thereof. Examples of substituted alkyls and aryls includes,but are not limited to, acyl radicals, alkylamino radicals, alkoxyradicals, aryloxy radicals, alkylthio radicals, dialkylamino radicals,alkoxycarbonyl radicals, aryloxycarbonyl radicals, carbamoyl radicals,alkyl- and dialkyl-carbamoyl radicals, acyloxy radicals, acylaminoradicals, arylamino radicals, and combinations thereof. More preferably,the hafnocene component useful in the present invention can berepresented by the formula:

(CpR₅)₂HfX₂  (2)

wherein each Cp is a cyclopentadienyl ligand and each is bound to thehafnium; each R is independently selected from hydrides and C₁ to C₁₀alkyls, most preferably hydrides and C₁ to C₅ alkyls; and X is selectedfrom the group consisting of hydride, halide, C₁ to C₁₀ alkyls and C₂ toC₁₂ alkenyls, and more preferably X is selected from the groupconsisting of halides, C₂ to C₆ alkylenes and C₁ to C₆ alkyls, and mostpreferably X is selected from the group consisting of chloride,fluoride, C₁ to C₅ alkyls and C₂ to C₆ alkylenes. In a most preferredembodiment, the hafnocene is represented by formula (2) above, whereinat least one R group is an alkyl as defined above, preferably a C₁ to C₅alkyl, and the others are hydrides. In a most preferred embodiment, eachCp is independently substituted with from one two three groups selectedfrom the group consisting of methyl, ethyl, propyl, butyl, and isomersthereof.

In one embodiment, the hafnocene based catalyst system is heterogeneous,i.e. the hafnocene based catalyst may further comprise a supportmaterial. The support material can be any material known in the art forsupporting catalyst compositions; for example an inorganic oxide; or inthe alternative, silica, alumina, silica-alumina, magnesium chloride,graphite, magnesia, titania, zirconia, and montmorillonite, any of whichcan be chemically/physically modified such as by fluoriding processes,calcining or other processes known in the art. In one embodiment thesupport material is a silica material having an average particle size asdetermined by Malvern analysis of from 1 to 60 mm; or in thealternative, 10 to 40 mm.

The hafnocene based catalyst system may further comprise an activator.Any suitable activator known to activate catalyst components towardsolefin polymerization may be suitable. In one embodiment, the activatoris an alumoxane; in the alternative methalumoxane such as described byJ. B. P. Soares and A. E. Hamielec in 3(2) POLYMER REACTION ENGINEERING131 200 (1995). The alumoxane may preferably be co-supported on thesupport material in a molar ratio of aluminum to hafnium (Al:Hf) rangingfrom 80:1 to 200:1, most preferably 90:1 to 140:1.

Such hafnium based catalyst systems are further described in details inthe U.S. Pat. No. 6,242,545 and U.S. Pat. No. 7,078,467, incorporatedherein by reference.

In application, the inventive polyethylene composition may be used tomanufacture shaped articles. Such articles may include, but are notlimited to, injection molded articles such as totes, trays, bins,containers, waste baskets, food storage containers, lids, pitchers, shoeboxes, assorted storage boxes, cloths storage containers, Christmasornament storage containers, photo storage containers, containers forthe storage of flour, sugar, cereal, ice-cream, crackers, and the like,yogurt cups, sour cream cup, and the likes; injection blow moldedarticles; co-extruded blow molded articles; injection stretch blowmolded articles; and compression molded articles. Different methods maybe employed to manufacture such articles. Suitable conversion techniquesinclude, but are not limited to, injection molding, injection blowmolding, co-extrusion blow molding, injection stretch blow molding, andcompression molding. Such techniques are generally well known. Preferredconversion techniques include, but are not limited to, injectionmolding.

In the injection molding process, the inventive polyethylene compositionis fed into an extruder via a hopper. The extruder conveys, heats,melts, and pressurizes the inventive polyethylene composition to a forma molten stream. The molten stream is forced out of the extruder underpressure through a nozzle into a relatively cool mold held closedthereby filling the mold. The melt cools and hardens until fully set-up.The mold then opens and the molded article, e.g. totes, dish pans, waistcontainers, bottle caps, is removed. The injection molded cap mayinclude a skirt that axially extends from the periphery of a base, andmay further include internal threads for securing the cap to acontainer.

In a blow molding process, e.g. a three step injection blow moldingprocess, the inventive polyethylene composition is melted, and then, itis formed into a tube via injection molding. The ends of the tube aresealed, except for an area in which the blowing air can enter. Thesealed tube is transported to a second station where the tube isinflated inside of a mold thereby taking the shape of the mold. In thethird station, the molded article, e.g. bottle, is cooled, and thenejected from the mold. If necessary, the molded article is then trimmed.

In compression molding process, a two-piece mold provides a cavityhaving the shape of a desired molded article. The mold is capable ofbeing heated or cooled. An appropriate amount of the inventivepolyethylene composition, preferably in a molten form, is loaded intothe lower half of the mold. The two parts of the mold are broughttogether under pressure. The inventive polyethylene composition, moltenby heat, is thereby welded into a continuous mass having the shape ofthe cavity. The continuous mass is hardened via chilling, underpressure, in the mold, thereby forming a compression molded article,e.g. bottle cap. The compression molded cap may include a skirt thataxially extends from the periphery of a base, and may further includeinternal threads for securing the cap to a container.

The injection molded articles according to the instant inventioncomprise a polyethylene composition comprising (1) less than or equal to100 percent by weight of the units derived from ethylene; and (2) lessthan 15 percent by weight of units derived from one or more α-olefincomonomers; wherein the polyethylene composition has a density in therange of 0.907 to 0.975 g/cm³, a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 3.62, a melt index (I₂) in therange of 2 to 1000 g/10 minutes, a molecular weight distribution(M_(z)/M_(w)) in the range of less than 2.5, vinyl unsaturation of lessthan 0.06 vinyls per one thousand carbon atoms present in the backboneof said composition.

The process for making an injection molded article according to theinstant invention comprises the steps of: (a) selecting a polyethylenecomposition comprising (1) less than or equal to 100 percent by weightof the units derived from ethylene; and (2) less than 15 percent byweight of units derived from one or more α-olefin comonomers; whereinthe polyethylene composition has a density in the range of 0.907 to0.975 g/cm³, a molecular weight distribution (M_(w)/M_(n)) in the rangeof 1.70 to 3.62, a melt index (I₂) in the range of 2 to 1000 g/10minutes, a molecular weight distribution (M_(w)/M_(n)) in the range ofless than 2.5, vinyl unsaturation of less than 0.06 vinyls per onethousand carbon atoms present in the backbone of the composition; (b)injection molding the polyethylene composition; and (c) thereby formingthe injection molded article.

EXAMPLES

The following examples illustrate the present invention but are notintended to limit the scope of the invention. The examples of theinstant invention demonstrate that the inventive polyethylenecomposition has a narrow molecular weight distribution, narrowcomposition distribution, and improved low and room temperature impactresistance while maintaining stiffness and processability properties.

Inventive Examples Catalyst Component Preparation

The hafnocene component can be prepared by techniques known in the art.For example, HfCl₄ (1.00 equiv.) can be added to ether at −30° C. to−50° C. and stirred to give a white suspension. The suspension can thenbe re-cooled to −30° C. to −50° C., and then lithiumpropylcyclopentadienide (2.00 equiv.) added in portions. The reactionwill turn light brown and become thick with suspended solid on addingthe lithium propylcyclopentadienide. The reaction can then be allowed towarm slowly to room temperature and stirred 10 to 20 hours. Theresultant brown mixture can then be filtered to give brown solid and astraw yellow solution. The solid can then be washed with ether as isknown in the art, and the combined ether solutions concentrated to undervacuum to give a cold, white suspension. Off-white solid product is thenisolated by filtration and dried under vacuum, with yields of from 70 to95%.

Catalyst Composition Preparation

The catalyst compositions should be made at a Al/Hf mole ratio of fromabout 80:1 to 130:1 and the hafnium loading on the finished catalystshould be from about 0.6 to 0.8 wt % Hf using the following generalprocedure. Methylaluminoxane (MAO) in toluene should be added to aclean, dry vessel and stirred at from 50 to 80 rpm and at a temperaturein the range of 60 to 100° F. Additional toluene can then be added whilestirring. The hafnocene can then be dissolved in an amount of tolueneand placed in the vessel with the MAO. The metallocene/MAO mixture canthen be stirred at for from 30 min to 2 hours. Next, an appropriateamount of silica (average particle size of from 22 to 28 μm, dehydratedat 600° C.) can be added and stirred for another hour or more. Theliquid can then be decanted and the catalyst composition dried atelevated temperature under flowing nitrogen while being stirred.

Polymerization Process

The ethylene/1-hexene copolymers were produced in accordance with thefollowing general procedure. The catalyst composition comprised a silicasupported bis(n-propylcyclopentadienyl) hafnium dichloride withmethalumoxane, the Al:Hf ratio being from about 80:1 to 130:1. Thecatalyst composition was injected dry into a fluidized bed gas phasepolymerization reactor. More particularly, polymerization was conductedin a 336.5-419.3 mm ID diameter gas-phase fluidized bed reactoroperating at approximately 2068 to 2586 kPa total pressure. The reactorbed weight was approximately 41-91 kg. Fluidizing gas was passed throughthe bed at a velocity of approximately 0.49 to 0.762 m per second. Thefluidizing gas exiting the bed entered a resin disengaging zone locatedat the upper portion of the reactor. The fluidizing gas then entered arecycle loop and passed through a cycle gas compressor and water-cooledheat exchanger. The shell side water temperature was adjusted tomaintain the reaction temperature to the specified value. Ethylene,hydrogen, 1-hexene and nitrogen were fed to the cycle gas loop justupstream of the compressor at quantities sufficient to maintain thedesired gas concentrations. Gas concentrations were measured by anon-line vapor fraction analyzer. Product (the inventive polyethyleneparticles) was withdrawn from the reactor in batch mode into a purgingvessel before it was transferred into a product bin. Residual catalystand activator in the resin was deactivated in the product drum with awet nitrogen purge. The catalyst was fed to the reactor bed through astainless steel injection tube at a rate sufficient to maintain thedesired polymer production rate. There were 6 separate polymerizationruns conducted using this general process, each with varying conditionsas elucidated in the Table I. Tables II-IV summarize the properties ofthe inventive polyethylene compositions 1-6 that resulted from each run.

Comparative Examples

The following comparative examples were provided.

Comparative example 1 is a high-density polyethylene (ethylene/hexenecopolymer) having a density of approximately 0.952 g/cm³, and a meltindex (I₂) of approximately 6.75 provided by The Dow Chemical Company™under the tradename of DMDA-8907 NT 7™. Comparative example 1 is acomparative example to the inventive example 1.

Comparative example 2 is a high-density polyethylene (ethylene/hexenecopolymer) having a density of approximately 0.954 g/cm³, and a meltindex (I₂) of approximately 20 provided by The Dow Chemical Company™under the tradename of DMDA-8920 NT 7™. Comparative example 2 is acomparative example to the inventive example 2.

Comparative example 3a is a high-density polyethylene (ethylene/hexenecopolymer) having a density of approximately 0.942 g/cm³, and a meltindex (I₂) of approximately 50 provided by The Dow Chemical Company™under the tradename of DMDA-8950 NT 7™. Comparative example 3a is acomparative example to the inventive example 3.

Comparative example 3b is a high-density polyethylene (ethylene/hexenecopolymer) having a density of approximately 0.952 g/cm³, and a meltindex (I₂) of approximately 66 provided by The Dow Chemical Company™under the tradename of DMDA-8965 NT 7™. Comparative example 3b isanother comparative example to the inventive example 3.

Comparative example 3c is a polyethylene (ethylene/octene copolymer)having a density of approximately 0.942 g/cm³, and a melt index (I₂) ofapproximately 60 from Nova Chemicals™ under the tradename of SurpassIFs542-R™. Comparative example 3c is another comparative example to theinventive example 3.

Comparative example 4a is a linear-low-density polyethylene(ethylene/butene copolymer) having a density of approximately 0.926g/cm³, and a melt index (I₂) of approximately 50 provided by The DowChemical Company™ under the tradename of DNDB-7147 NT 7™. Comparativeexample 4a is a comparative example to the inventive example 4.

Comparative example 4b was a sample from Nova Chemicals™ under thetradename of Surpass IFs730R™. Comparative example 4b is anothercomparative example to the inventive example 4.

Comparative example 5 is a linear-low-density polyethylene(ethylene/hexene copolymer) having a density of approximately 0.929g/cm³, and a melt index (I₂) of approximately 100 provided by The DowChemical Company™ under the tradename of DNDB-1077 NT 7™. Comparativeexample 5 is a comparative example to the inventive example 5.

Comparative example 6a is a linear-low-density polyethylene(ethylene/hexene copolymer) having a density of approximately 0.933g/cm³, and a melt index (I₂) of approximately 155 provided by The DowChemical Company™ under the tradename of DNDB-1082 NT 7™. Comparativeexample 6a is a comparative example to the inventive example 6.

Comparative example 6b is a polyethylene (ethylene/octene copolymer)having a density of approximately 0.932 g/cm³, and a melt index (I₂) ofapproximately 150 from Nova Chemicals™ under the tradename of SurpassIFs932-R™. Comparative example 6b is another comparative example to theinventive example 6.

Tables V-VII summarize the properties of the comparative polyethylenecompositions.

Test Methods

Test methods include the following:

Density (g/cm³) was measured according to ASTM-D 792-03, Method B, inisopropanol. Specimens were measured within 1 hour of molding afterconditioning in the isopropanol bath at 23° C. for 8 min to achievethermal equilibrium prior to measurement. The specimens were compressionmolded according to ASTM D-4703-00 Annex A with a 5 min initial heatingperiod at about 190° C. and a 15° C./min cooling rate per Procedure C.The specimen was cooled to 45° C. in the press with continued coolinguntil “cool to the touch.”

Melt index (I₂) was measured at 190° C. under a load of 2.16 kgaccording to ASTM D-1238-03.

Melt index (I₅) was measured at 190° C. under a load of 5.0 kg accordingto ASTM D-1238-03.

Melt index (I₁₀) was measured at 190° C. under a load of 10.0 kgaccording to ASTM D-1238-03.

Melt index (I₂₁) was measured at 190° C. under a load of 21.6 kgaccording to ASTM D-1238-03.

Weight average molecular weight (M_(w)) and number average molecularweight (M_(n)) were determined according to methods known in the artusing triple detector GPC, as described herein below.

The molecular weight distributions of the ethylene polymers weredetermined by gel permeation chromatography (GPC). The chromatographicsystem consisted of a Waters (Millford, Mass.) 150° C. high temperaturegel permeation chromatograph, equipped with a Precision Detectors(Amherst, Mass.) 2-angle laser light scattering detector Model 2040. The15° angle of the light scattering detector was used for calculationpurposes. Data collection was performed using Viscotek TriSEC softwareversion 3 and a 4-channel Viscotek Data Manager DM400. The system wasequipped with an on-line solvent degas device from Polymer Laboratories.The carousel compartment was operated at 140° C. and the columncompartment was operated at 150° C. The columns used were four Shodex HT806M 300 mm, 13 μm columns and one Shodex HT803M 150 mm, 12 μm column.The solvent used was 1,2,4 trichlorobenzene. The samples were preparedat a concentration of 0.1 grams of polymer in 50 milliliters of solvent.The chromatographic solvent and the sample preparation solvent contained200 μg/g of butylated hydroxytoluene (BHT). Both solvent sources werenitrogen sparged. Polyethylene samples were stirred gently at 160° C.for 4 hours. The injection volume used was 200 microliters, and the flowrate was 0.67 milliliters/min Calibration of the GPC column set wasperformed with 21 narrow molecular weight distribution polystyrenestandards, with molecular weights ranging from 580 to 8,400,000 g/mol,which were arranged in 6 “cocktail” mixtures with at least a decade ofseparation between individual molecular weights. The standards werepurchased from Polymer Laboratories (Shropshire, UK). The polystyrenestandards were prepared at 0.025 grams in 50 milliliters of solvent formolecular weights equal to, or greater than, 1,000,000 g/mol, and 0.05grams in 50 milliliters of solvent for molecular weights less than1,000,000 g/mol. The polystyrene standards were dissolved at 80° C. withgentle agitation for 30 minutes. The narrow standards mixtures were runfirst, and in order of decreasing highest molecular weight component, tominimize degradation. The polystyrene standard peak molecular weightswere converted to polyethylene molecular weights using the followingequation (as described in Williams and Ward, J. Polym. Sci., Polym.Let., 6, 621 (1968)):

Mpolyethylene=A×(Mpolystyrene)^(B),

where M is the molecular weight, A has a value of 0.41 and B is equal to1.0. The Systematic Approach for the determination of multi-detectoroffsets was done in a manner consistent with that published by Balke,Mourey, et al. (Mourey and Balke, Chromatography Polym. Chpt 12, (1992)and Balke, Thitiratsakul, Lew, Cheung, Mourey, Chromatography Polym.Chpt 13, (1992)), optimizing dual detector log results from Dow broadpolystyrene 1683 to the narrow standard column calibration results fromthe narrow standards calibration curve using in-house software. Themolecular weight data for off-set determination was obtained in a mannerconsistent with that published by Zimm (Zimm, B. H., J. Chem. Phys., 16,1099 (1948)) and Kratochvil (Kratochvil, P., Classical Light Scatteringfrom Polymer Solutions, Elsevier, Oxford, N.Y. (1987)). The overallinjected concentration used for the determination of the molecularweight was obtained from the sample refractive index area and therefractive index detector calibration from a linear polyethylenehomopolymer of 115,000 g/mol molecular weight, which was measured inreference to NIST polyethylene homopolymer standard 1475. Thechromatographic concentrations were assumed low enough to eliminateaddressing 2^(nd) Virial coefficient effects (concentration effects onmolecular weight). Molecular weight calculations were performed usingin-house software. The calculation of the number-average molecularweight, weight-average molecular weight, and z-average molecular weightwere made according to the following equations, assuming that therefractometer signal is directly proportional to weight fraction. Thebaseline-subtracted refractometer signal can be directly substituted forweight fraction in the equations below. Note that the molecular weightcan be from the conventional calibration curve or the absolute molecularweight from the light scattering to refractometer ratio. An improvedestimation of z-average molecular weight, the baseline-subtracted lightscattering signal can be substituted for the product of weight averagemolecular weight and weight fraction in equation (2) below:

$\begin{matrix}{{\left. {{{\left. {{{\left. a \right)\mspace{14mu} \overset{\_}{Mn}} = \frac{\sum\limits^{i}{Wf}_{i}}{\sum\limits^{i}\left( {{Wf}_{i}/M_{i}} \right)}}b} \right)\mspace{14mu} \overset{\_}{Mw}} = \frac{\sum\limits^{i}\left( {{Wf}_{i}*M_{i}} \right)}{\sum\limits^{i}{Wf}_{i}}}c} \right)\mspace{14mu} \overset{\_}{Mz}} = \frac{\sum\limits^{i}\left( {{Wf}_{i}*M_{i}^{2}} \right)}{\sum\limits^{i}\left( {{Wf}_{i}*M_{i}} \right)}} & (2)\end{matrix}$

Monomodal distribution was characterized according to the weightfraction of the highest temperature peak in temperature rising elutionfractionation (typically abbreviated as “TREF”) data as described, forexample, in Wild et al., Journal of Polymer Science, Poly. Phys. Ed.,Vol. 20, p. 441 (1982), in U.S. Pat. No. 4,798,081 (Hazlitt et al.), orin U.S. Pat. No. 5,089,321 (Chum et al.), the disclosures of all ofwhich are incorporated herein by reference. In analytical temperaturerising elution fractionation analysis (as described in U.S. Pat. No.4,798,081 and abbreviated herein as “ATREF”), the composition to beanalyzed is dissolved in a suitable hot solvent (for example, 1,2,4trichlorobenzene), and allowed to crystallized in a column containing aninert support (for example, stainless steel shot) by slowly reducing thetemperature. The column was equipped with both an infra-red detector anda differential viscometer (DV) detector. An ATREF-DV chromatogram curvewas then generated by eluting the crystallized polymer sample from thecolumn by slowly increasing the temperature of the eluting solvent(1,2,4 trichlorobenzene). The ATREF-DV method is described in furtherdetail in WO 99/14271, the disclosure of which is incorporated herein byreference.

Long Chain Branching was determined according to the methods known inthe art, such as gel permeation chromatography coupled with low anglelaser light scattering detector (GPC-LALLS) and gel permeationchromatography coupled with a differential viscometer detector (GPC-DV).

Short chain branch distribution breadth (SCBDB) was determined based inthe data obtained via analytical temperature rising elutionfractionation (ATREF) analysis, described hereinbelow in furtherdetails. First, a cumulative distribution of the elution curve wascalculated beginning at 30° C. and continuing to and including 109° C.From the cumulative distribution, temperatures were selected at 5 weightpercent (T₅) and 95 weight percent (T₉₅). These two temperatures werethen used as the bounds for the SCBDB calculation. The SCBDB is thencalculated from the following equation:

${S\; C\; B\; D\; B} = \sqrt{\frac{\sum\limits_{i}{w_{i}\left( {T_{i} - T_{w}} \right)}^{2}}{\sum\limits_{i}w_{i}}}$

for all T_(i) including and between T₅ and T₉₅. T_(i) is the temperatureat the ith point on the elution curve, w_(i) is the weight fraction ofmaterial from each temperature on the elution curve, and T_(w) is theweight-averaged temperature of the elution curve (Σ(w_(i)T_(i))/Σw_(i))between and including T₅ and T₉₅.

Analytical temperature rising elution fractionation (ATREF) analysis wasconducted according to the method described in U.S. Pat. No. 4,798,081and Wilde, L.; Ryle, T. R.; Knobeloch, D. C.; Peat, I. R.; Determinationof Branching Distributions in Polyethylene and Ethylene Copolymers, J.Polym. Sci., 20, 441-455 (1982), which are incorporated by referenceherein in their entirety. The composition to be analyzed was dissolvedin trichlorobenzene and allowed to crystallize in a column containing aninert support (stainless steel shot) by slowly reducing the temperatureto 20° C. at a cooling rate of 0.1° C./min. The column was equipped withan infrared detector. An ATREF chromatogram curve was then generated byeluting the crystallized polymer sample from the column by slowlyincreasing the temperature of the eluting solvent (trichlorobenzene)from 20 to 120° C. at a rate of 1.5° C./min.

Comonomer content was measured using C₁₃ NMR, as discussed in Randall,Rev. Macromol. Chem. Chys., C29 (2&3), pp. 285-297, and in U.S. Pat. No.5,292,845, the disclosures of which are incorporated herein by referenceto the extent related to such measurement. The samples were prepared byadding approximately 3 g of a 50/50 mixture oftetrachloroethane-d2/orthodichlorobenzene that was 0.025M in chromiumacetylacetonate (relaxation agent) to 0.4 g sample in a 10 mm NMR tube.The samples were dissolved and homogenized by heating the tube and itscontents to 150° C. The data was collected using a JEOL Eclipse 400 MHzNMR spectrometer, corresponding to a 13 C resonance frequency of 100.6MHz. Acquisition parameters were selected to ensure quantitative 13 Cdata acquisition in the presence of the relaxation agent. The data wasacquired using gated 1H decoupling, 4000 transients per data file, a 4.7sec relaxation delay and 1.3 second acquisition time, a spectral widthof 24,200 Hz and a file size of 64K data points, with the probe headheated to 130° C. The spectra were referenced to the methylene peak at30 ppm. The results were calculated according to ASTM method D5017-91.

Melt temperature and crystallization temperature were measured viaDifferential Scanning Calorimetry (DSC). All of the results reportedhere were generated via a TA Instruments Model Q1000 DSC equipped withan RCS (refrigerated cooling system) cooling accessory and an autosampler. A nitrogen purge gas flow of 50 ml/min was used throughout. Thesample was pressed into a thin film using a press at 175° C. and 1500psi (10.3 MPa) maximum pressure for about 15 seconds, then air-cooled toroom temperature at atmospheric pressure. About 3 to 10 mg of materialwas then cut into a 6 mm diameter disk using a paper hole punch, weighedto the nearest 0.001 mg, placed in a light aluminum pan (ca 50 mg) andthen crimped shut. The thermal behavior of the sample was investigatedwith the following temperature profile: The sample was rapidly heated to180° C. and held isothermal for 3 minutes in order to remove anyprevious thermal history. The sample was then cooled to −40° C. at 10°C./min cooling rate and was held at −40° C. for 3 minutes. The samplewas then heated to 150° C. at 10° C./min heating rate. The cooling andsecond heating curves were recorded.

Vinyl unsaturations were measured according to ASTM D-6248-98.

Trans unsaturations were measured according to ASTM D-6248-98.

Methyl groups were determined according to ASTM D-2238-92.

Resin stiffness was characterized by measuring the Flexural Modulus at 5percent strain and Secant Modulii at 1 percent and 2 percent strain, anda test speed of 0.5 inch/min (13 mm/min) according to ASTM D-790-99Method B.

Tensile testing is determined via ASTM D-638 at 2 inches per minutestrain rate.

Tensile impact was determined according to ASTM D-1822-06.

The capillary viscosity measured at 190° C. on a Goettfert Rheograph2003 fitted with a flat entrance (180°) die of length 20 mm and diameterof 1 mm at apparent shear rates ranging from 100 to 6300 s⁻¹.Rabinowitsch correction was applied to account for the shear thinningeffect. The corrected shear rate and shear viscosity were reportedherein.

The present invention may be embodied in other forms without departingfrom the spirit and the essential attributes thereof, and, accordingly,reference should be made to the appended claims, rather than to theforegoing specification, as indicating the scope of the invention.

TABLE I Measurement Units Inventive 1 Inventive 2 Inventive 3 Inventive4 Inventive 5 Inventive 6 Reactor Temperature ° C. 95.0 95.0 85.0 85.085.0 85.0 Isopentane % mol % 4.8 5.3 5.2 5.3 5.6 5.0 Ethylene PartialPressure psia 225.1 225.2 225.0 150.0 150.0 150.3 C6/C2 molar ratiounitless 0.0016 0.0026 0.0042 0.0110 0.0115 0.0115 Hydrogen VaporConcentration ppm 320 500 550 703 720 777 Continuity Additive amount inppm (w) 6 3 6 8 8 8 resin Hf amount in resin ppm (w) 0.87 0.88 0.57 2.180.93 0.83 Al amount in resin ppm (w) 11.3 12.5 9.8 62.2 26.5 34.3

TABLE II Measurement Units Inventive 1 Inventive 2 Inventive 3 Inventive4 Inventive 5 Inventive 6 Density g/cm³ 0.954 0.9542 0.9523 0.93140.9334 0.9335 I₂ g/10 min 10.4 36.9 74.6 77.03 136.7 177.3 I₅ g/10 min27.2 88.8 220.5 203.3 416.2 483.6 I₁₀ g/10 min 65.8 260 — — — — I₂₁ g/10min 201.3 785 — — — — I_(10/)I₂ — 6.3 7.1 — — — — I_(21/)I₂ — 19.3 21.3— — — — Conventional GPC Mn g/mol 19600 13700 11970 9900 7640 7460 Mwg/mol 62670 43990 36330 32540 27660 25610 Mz g/mol 127700 89120 7163069700 61100 56800 Mw/Mn unitless 3.20 3.21 3.04 3.29 3.62 3.43 Mz/Mwunitless 2.04 2.03 1.97 2.14 2.21 2.22 Absolute GPC Mn absolute g/mol18204.00 11687 10213 10869 8249 8408 Mw absolute g/mol 62770.00 4094034660 33330 28110 25740 Mz (BB) g/mol 131000.00 91300 78500 63700 6480059000 Mz (BB)/Mw (abs) unitless 2.09 2.23 2.26 1.91 2.31 2.29 ShearViscosity at ~3000 s⁻¹ Pa-s 132.4 73.2 51.4 49.7 32.5 26.6 methyls per1000 C's 0.87 1.910 2.880 9.62 10.4 11.000 trans per 1000 C's 0.0330.019 0.015 0.004 0.010 0.009 vinyls per 1000 C's 0.002 0.003 0.0000.006 0.004 0.004

TABLE III Measurement Units Inventive 1 Inventive 2 Inventive 3Inventive 4 Inventive 5 Inventive 6 T (crystallization) DSC ° C. 116.7116.8 116.2 109.0 109.9 110.2 T (melt) DSC ° C. 130.4 128.6 127.7 119.2120.0 119.8 Heat of Fusion (DSC) J/g 192.2 191.3 188.0 166.6 171.7 173.3ATREF Data HD Fraction % 86.5 89.0 79.8 2.1 1.3 1.3 Temperature Min. °C. 86.4 86.2 86.0 95.8 96.0 96.0 Percent Solubles % 8.5 4.3 7.3 2.7 13.515.4 Average Mv g/mol 64510 32099 28435 29908 25348 18597 SCBD Breadth °C. 2.93 3.2 4.86 5.55 6.67 7.7

TABLE IV Measurement Units Inventive 1 Inventive 2 Inventive 3 Inventive4 Inventive 5 Inventive 6 Tensile Plaque Thickness inches 0.0666 0.06280.066 0.0626 0.0644 0.0647 Tensile Toughness inch-lb 296.00 19.00 3.0035.96 18.22 13.13 Tensile Strain at Break % 791.22 44.35 6.75 162.3871.78 43.73 Tensile Stress at Break psi 2949 3109 3786 1425 1412 1584Yield Strain % 100.158 2.576 2.052 4.24 4.202 3.1575 Yield Stress psi3499 2719 2388 1345 1593 1547 Tensile Impact ft-lbs/in² — — 12.1 44.936.3 23 Flexural Modulus psi 176115 220474 195374 108993 116423 1188941% Secant Modulus psi 143381 182678 165717 81882 87946 88596 2% SecantModulus psi 120762 152970 141023 95824 102659 103300

TABLE V Comparative Comparative Comparative Comparative ComparativeMeasurement Units 1 2 3a 3b 3c Density g/cm³ 0.951 0.9565 0.944 0.95410.9431 I₂ g/10 min 6.6 18.2 43.2 56.0 55.8 I₅ g/10 min 17.5 53.0 128.9157.7 145.5 I₁₀ g/10 min 47.1 138.6 — — — I₂₁ g/10 min 178.0 539.4 — — —I_(10/)I₂ — 7.1 7.6 — — — I_(21/)I₂ — 26.8 29.7 — — — Conventional GPCMn g/mol 19750 13960 10790 10690 10350 Mw g/mol 73460 55210 44670 4188037570 Mz g/mol 199800 154100 140600 127600 80750 Mw/Mn unitless 3.723.95 4.14 3.92 3.63 Mz/Mw unitless 2.72 2.79 3.15 3.05 2.15 Absolute GPCMn absolute g/mol 17576 12348 9812 9122 12192 Mw absolute g/mol 12723091130 65860 71170 38560 Mz (BB) g/mol 765200 643300 550700 712300 89300Mz (BB)/Mw (abs) unitless 6.01 7.06 8.36 10.01 2.32 Shear Viscosity at~3000 s⁻¹ Pa-s 129.2 85.1 56.0 50.7 51.6 methyls per 1000 C's 1.32 1.8405.830 3.220 4.060 trans per 1000 C's 0.001 0.002 0.002 0.002 0.128vinyls per 1000 C's 0.110 0.098 0.082 0.096 0.096 ComparativeComparative Comparative Comparative Comparative Measurement Units 4a 4b5 6a 6b Density g/cm³ 0.9269 0.9303 0.9306 0.9343 0.9332 I₂ g/10 min45.1 80.5 74.3 123.1 143.5 I₅ g/10 min 134.2 212.2 218.6 435.0 471.6 I₁₀g/10 min — — — — — I₂₁ g/10 min — — — — — I_(10/)I₂ — — — — — —I_(21/)I₂ — — — — — — Conventional GPC Mn g/mol 8580 9180 6950 6710 7890Mw g/mol 38960 32030 34560 29800 27860 Mz g/mol 120100 81800 12900097100 74400 Mw/Mn unitless 4.54 3.49 4.97 4.44 3.53 Mz/Mw unitless 3.082.55 3.73 3.26 2.67 Absolute GPC Mn absolute g/mol 9342 9881 7047 72128700 Mw absolute g/mol 52170 32110 43170 37700 29470 Mz (BB) g/mol368200 79100 302400 196400 70900 Mz (BB)/Mw (abs) unitless 7.06 2.467.00 5.21 2.41 Shear Viscosity at ~3000 s⁻¹ Pa-s 54.2 39.1 36.5 28.827.3 methyls per 1000 C's 17.60 9.62 13.9 13.300 9.640 trans per 1000C's 0.057 0.258 0.008 0.007 0.338 vinyls per 1000 C's 0.088 0.099 0.0750.071 0.083

TABLE VI Measurement Units Comparative 1 Comparative 2 Comparative 3aComparative 3b Comparative 3c T (crystallization) DSC ° C. 117.1 116.5114.1 115.4 113.5 T (melt) DSC ° C. 130.7 130.0 126.6 128.9 125.1Melting Energy (DSC) J/g 190.5 194.9 174.4 190.1 170.8 ATREF Data HDFraction % 81.3 80.6 60.7 73.2 59.4 Temperature Min. ° C. 86.0 86.1 86.086.1 87.3 Percent Solubles % 11.9 11.4 7.7 9.7 10.3 Average Mv g/mol59095 40234 27454 36059 38683 SCBD Breadth ° C. 4.22 4.47 5.32 6.63 4.93Comparative Comparative Measurement Units Comparative 4a 4b Comparative5 Comparative 6a 6b T (crystallization) DSC ° C. 107.9 107.6 113.0 112.3108.8 T (melt) DSC ° C. 120.4 117.3 124.4 124.3 118.4 Melting Energy(DSC) J/g 156.1 163.2 164.4 172.2 168.7 ATREF Data HD Fraction % 14.01.0 37.5 33.5 0.6 Temperature Min. ° C. 93.4 96.0 86.4 87.5 96.0 PercentSolubles % 18.3 11.1 21.6 16.9 16.1 Average Mv g/mol 24340 25990 2397015361 19106 SCBD Breadth ° C. 12.52 7.05 11.88 13.12 8.32

TABLE VII Measurement Units Comparative 1 Comparative 2 Comparative 3aComparative 3b Comparative 3c Tensile Plaque Thickness inches — — 0.0620.062 0.0682 Tensile Toughness inch-lb — — 6.33 2.94 14.96 TensileStrain at Break % 1050.70 266.56 14.22 6.24 37.70 Tensile Stress atBreak psi 3355 2013 3179 3855 2548 Yield Strain % 4.232 3.982 2.7721.368 3.052 Yield Stress psi 3641 3776 2505 2382 1923 Tensile Impactft-lbs/in² — — 16.3 3.36 33.4 Flexural Modulus psi 212581 225307 163429198625 161826 1% Secant Modulus psi 167433 182542 130873 180714 1338612% Secant Modulus psi 139287 152835 106919 155019 114550 ComparativeComparative Measurement Units Comparative 4a 4b Comparative 5Comparative 6a 6b Tensile Plaque Thickness inches 0.066 0.0666 0.06540.0634 0.0648 Tensile Toughness inch-lb 36.85 15.80 30.49 10.74 4.96Tensile Strain at Break % 134.50 67.56 136.32 22.88 15.64 Tensile Stressat Break psi 1094 785 1154 2240 2290 Yield Strain % 4.082 3.962 3.0643.346 3.12 Yield Strength psi 1102 1067 1559 1750 1466 Tensile Impactft-lbs/in² 27.6 30.2 29.7 15.1 9.69 Flexural Modulus psi 92861 89836106521 126395 99611 1% Secant Modulus psi 69924 68203 79416 93241 753752% Secant Modulus psi 81345 78959 92929 109648 87382

We claim:
 1. A polyethylene composition comprising: less than or equalto 100 percent by weight of the units derived from ethylene; less than15 percent by weight of units derived from one or more α-olefincomonomers; wherein said polyethylene composition has a density in therange of 0.907 to 0.975 g/cm³, a molecular weight distribution(M_(w)/M_(n)) in the range of 1.70 to 3.62, a melt index (I₂) in therange of 2 to 1000 g/10 minutes, a molecular weight distribution(M_(z)/M_(w)) in the range of less than 2.5, vinyl unsaturation of lessthan 0.06 vinyls per one thousand carbon atoms present in the backboneof said composition.
 2. The polyethylene composition according to claim1, wherein said polyethylene composition has a molecular weightdistribution (M_(w)/M_(n)) of less than [(−16.18))(D)]+18.83, wherein Dis the density of said polyethylene composition in the range of greaterthan 0.940 g/cm³ to less than or equal to 0.975 g/cm³.
 3. Thepolyethylene composition according to claim 1, wherein said polyethylenecomposition has a short chain branching distribution breadth (SCBDB)expressed in ° C. of less than or equal to [0.025 (I₂)+4.08], wherein I₂is melt index expressed in g/10 min, and wherein said composition has adensity in the range of equal or greater than 0.930 g/cm³ to less than0.940 g/cm³.
 4. The polyethylene composition according to claim 1,wherein said polyethylene composition has a short chain branchingdistribution breadth (SCBDB) expressed in ° C. of less than or equal to[0.0312 (I₂)+2.87], wherein I₂ is melt index expressed in g/10 min, andwherein said composition has a density in the range of equal or greaterthan 0.940 g/cm³.
 5. The polyethylene composition according to claim 1,wherein said polyethylene composition has a tensile impact expressed inft-lb/in² of equal or greater than[(−6.53*10⁻⁵)(x⁴)]+[(1.3*10⁻²)(x³)]−[(9.68*10⁻¹)(x²)]+[(3.22*10)(x)]−[(3.69*10²)],wherein x is the shear viscosity of said composition expressed inPascal-s at 3000 s⁻¹ shear rate measured at 190° C., and wherein theshear viscosity is in the range of 25 to 55 Pascal-s at 3000 s⁻¹ shearrate measured at 190° C., and wherein the modulus of said composition isin the range of 75,000 to 115,000 psi.
 6. The polyethylene compositionaccording to claim 1, wherein said polyethylene composition has adensity in the range of 0.924 to 0.930 g/cm³, and a melt index (I₂) inthe range of 40 to 80 g/10 minutes.
 7. The polyethylene compositionaccording to claim 1, wherein said polyethylene composition has adensity in the range of 0.926 to 0.936 g/cm³, and a melt index (I₂) inthe range of 80 to 250 g/10 minutes.
 8. The polyethylene compositionaccording to claim 1, wherein said polyethylene composition has adensity in the range of 0.940 to 0.946 g/cm³, and a melt index (I₂) inthe range of 100 to 300 g/10 minutes.
 9. The polyethylene compositionaccording to claim 1, wherein said polyethylene composition has adensity in the range of 0.946 to 0.953 g/cm³, and a melt index (I₂) inthe range of 60 to 110 g/10 minutes.
 10. The polyethylene compositionaccording to claim 1, wherein said polyethylene composition has adensity in the range of 0.948 to 0.956 g/cm³, and a melt index (I₂) inthe range of 30 to 90 g/10 minutes.
 11. The polyethylene compositionaccording to claim 1, wherein said polyethylene composition has adensity in the range of 0.946 to 0.956 g/cm³, and a melt index (I₂) inthe range of 3 to 30 g/10 minutes.
 12. The polyethylene compositionaccording to claim 1, wherein said polyethylene composition has lessthan 2 peaks on an elution temperature-eluted amount curve determined bycontinuous temperature rising elution fraction method at equal or above30° C., wherein the purge peak which is below 30° C. is excluded. 13.The polyethylene composition according to claim 1, wherein saidpolyethylene composition comprises less than 11 percent by weight of theunits derived from one or more α-olefin comonomers.
 14. The polyethylenecomposition according to claim 1, wherein said polyethylene compositionis substantially free of long chain branching.
 15. The polyethylenecomposition according to claim 1, wherein said polyethylene compositioncomprises less than 100 parts by weight of a hafnium based metallocenecatalyst per one million parts of polyethylene composition.
 16. Thepolyethylene composition according to claim 1, wherein said polyethylenecomposition has a melt flow ratio (I₂₁/I₂) in the range of 17-24. 17.The polyethylene composition according to claim 1, wherein saidpolyethylene composition has a melt index I₂₁ in the range of 34 to23500 g/10 minutes.
 18. A process for producing a polyethylenecomposition comprising the steps of: (co)polymerizing ethylene andoptionally one or more α-olefin comonomers in the presence of a hafniumbased metallocene catalyst via a gas phase (co)polymerization process ina single stage reactor; thereby producing said polyethylene compositionhaving a density in the range of 0.907 to 0.975 g/cm³, a molecularweight distribution (M_(w)/M_(n)) in the range of 1.70 to 3.62, a meltindex (I₂) in the range of 2 to 1000 g/10 minutes, a molecular weightdistribution (M_(z)/M_(w)) in the range of less than 2.5, and a vinylunsaturation of less than 0.06 vinyls per one thousand carbon atomspresent in the backbone of said composition.
 19. An injection moldedarticle comprising the polyethylene composition of claim 1.